Direct Synthesis and Characterization of Hydrophilic Cu-Deficient Copper Indium Sulfide Quantum Dots

Copper indium sulfide (CIS) nanocrystals constitute a promising alternative to cadmium- and lead-containing nanoparticles. We report a synthetic method that yields hydrophilic, core-only CIS quantum dots, exhibiting size-dependent, copper-deficient composition and optical properties that are suitable for direct coupling to biomolecules and nonradiative energy transfer applications. To assist such applications, we complemented previous studies covering the femtosecond-picosecond time scale with the investigation of slower radiative and nonradiative processes on the nanosecond time scale, using both time-resolved emission and transient absorption. As expected for core particles, relaxation occurs mainly nonradiatively, resulting in low, size-dependent photoluminescence quantum yield. The nonradiative relaxation from the first excited band is wavelength-dependent with lifetimes between 25 and 150 ns, reflecting the size distribution of the particles. Approximately constant lifetimes of around 65 ns were observed for nonradiative relaxation from the defect states at lower energies. The photoluminescence exhibited a large Stokes shift. The band gap emission decays on the order of 10 ns, while the defect emission is further red-shifted, and the lifetimes are on the order of 100 ns. Both sets of radiative lifetimes are wavelength-dependent, increasing toward longer wavelengths. Despite the low radiative quantum yield, the aqueous solubility and long lifetimes of the defect states are compatible with the proposed role of CIS quantum dots as excitation energy donors to biological molecules.

Emergence of CuInS2 derived photocatalyst for environmental remediation and energy conversion

Hydrogen production, catalytic organic synthesis, carbon dioxide reduction, environmental purification, and other major fields have all adopted photocatalytic technologies due to their eco-friendliness, ease of use, and reliance on sunlight as the driving force. Photocatalyst is the key component of photocatalytic technology. Thus, it is of utmost importance to produce highly efficient, stable, visible-light-responsive photocatalysts. CIS stands out among other visible-light-response photocatalysts for its advantageous combination of easy synthesis, non-toxicity, high stability, and suitable band structure. In this study, we took a brief glance at the synthesis techniques for CIS after providing a quick introduction to the fundamental semiconductor features, including the crystal and band structures of CIS. Then, we discussed the ways doping, heterojunction creation, p-n heterojunction, type-II heterojunction, and Z-scheme may be used to modify CIS's performance. Subsequently, the applications of CIS towards pollutant degradation, CO2 reduction, water splitting, and other toxic pollutants remediation are reviewed in detail. Finally, several remaining problems with CIS-based photocatalysts are highlighted, along with future potential for constructing more superior photocatalysts.

Dye-induced photoluminescence quenching of quantum dots: role of excited state lifetime and confinement of charge carriers

We investigate the role of quantum confinement and photoluminescence (PL) lifetime of photoexcited charge carriers in semiconductor core/shell quantum dots (QDs) via PL quenching due to surface modification. Surface modification is controlled by varying the number of dye molecules adsorbed onto the QD shell surface forming QD-dye nanoassemblies. We selected CuInS₂/ZnS (CIS) and InP/ZnS (InP) core/shell QDs exhibiting relatively weak (664 meV) and strong (1194 meV) confinement potentials for the conduction band electron. Moreover, the difference in the emission mechanism gives rise to a long and short excited state lifetime of CIS (ca. 290 ns) and InP (ca. 37 ns) QDs. Dye molecules of different ionic characters (rhodamine 575: zwitterionic and rhodamine 560: cationic) are used as quenchers. A detailed analysis of Stern-Volmer data shows that (i) quenching is generally more pronounced in CIS-dye assemblies as compared to InP-dye assemblies, (ii) dynamic quenching is dominating in all QD-dye assemblies with only a minor contribution from static quenching and (iii) the cationic dye shows a stronger interaction with the QD shell surface than the zwitterionic dye. Observations (i) and (ii) can be explained by the differences in the amplitude of the electronic component of the exciton wavefunction near the dye binding sites in both QDs, which results in the breaking up of the electron-hole pair and favors charge trapping. Observation (iii) can be attributed to the variations in electrostatic interactions between the negatively charged QD shell surface and the cationic and zwitterionic dyes, with the former exhibiting a stronger interaction. Moreover, the long lifetime of CIS QDs facilitates us to easily probe different time scales of the trapping processes and thus differentiate the origins of static and dynamic quenching components that appear in the Stern-Volmer analysis.

Interfacial S-O bonds specifically boost Z-scheme charge separation in a CuInS2/In2O3 heterojunction for efficient photocatalytic activity

Reducing the recombination rate of photoexcited electron-hole pairs is always a great challenging work for the photocatalytic technique. In response to this issue, herein, a novel Z-scheme CuInS2/In2O3 with interfacial S-O linkages was synthesized by a hydrothermal and subsequently annealing method. The Fourier transform infrared (FT-IR) and X-ray photoelectron spectrometer (XPS) measurements confirmed the formation of covalent S-O bonds between CuInS2 and In2O3. The quenching and electron spin resonance (ESR) tests revealed the Z-scheme transfer route of photogenerated carriers over the CuInS2/In2O3 heterojunctions, which was further verified theoretically via density functional theory (DFT) calculations. As expected, the CuInS2/In2O3 heterojunctions showed significantly boosted photocatalytic activities for lomefloxacin degradation and Cr(vi) reduction under visible light illumination compared with the bare materials. Accordingly, a synergistic photocatalytic mechanism of Z-scheme heterostructures and interfacial S-O bonding was proposed, in which the S-O linkage could act as a specific bridge to modify the Z-scheme manner for accelerating the interfacial charge transmission. Furthermore, the CuInS2/In2O3 heterojunction also exhibited excellent performance perceived in the stability and reusability tests. This work provides a new approach for designing and fabricating novel Z-scheme heterostructures with a high-efficiency charge transfer route.

Glow and Flash Adjustable Chemiluminescence with Tunable Waveband from the Same CuInS2@ZnS Nanocrystal Luminophore

All commercial chemiluminescence (CL) assays are conducted with either glow or flash CL of eye-visible waveband from chemical luminophores. Herein, glow and flash, as well as waveband adjustable CL from the same nanoparticle luminophore of thiol-capped CuInS₂@ZnS nanocrystals (CIS@ZnS-Thiol), are proposed via extensively exploiting the differed redox nature of CL triggering reagents. Taking thiosalicylic acid (TSA) as the model thiol-capping agent, the electron-injection-initiated charge transfer between CIS@ZnS-TSA and reductant can bring out efficient glow CL while the hole-injection-initiated charge transfer between CIS@ZnS-TSA and oxidant can give off obvious flash CL under optimum conditions. The maximum emission wavelength for CL of CIS@ZnS-TSA is adjustable from 730 nm to 823 nm via employing different triggering agents. Promisingly, the coexistent reductant of N₂H₄·H₂O and oxidant of H₂O₂ can be employed as dual triggering reagents to trigger eye-visible and highly efficient flash CL from CIS@ZnS-TSA. The maximum emission intensity for flash CL of CIS@ZnS-TSA/N₂H₄-H₂O₂ is 101-fold greater than the glow CL of CIS@ZnS-TSA/N₂H₄ and 22-fold greater than the flash CL of CIS@ZnS-TSA/H₂O₂, respectively. The flash CL from CIS@ZnS-TSA/N₂H₄-H₂O₂ is qualified for highly sensitive and selective CL immunoassay in a commercialized typical procedure with the entire operating process manually terminated within 35 min.

Photoelectrochemical Application and Charge Transport Dynamics of a Water-Stable Organic-Inorganic Halide (C6H4NH2CuCl2I) Film in Aqueous Solution

A water-stable thin film composed of C₆H₄NH₂CuCl₂I was fabricated using spin-coating precursor solutions that dissolved equimolar amounts of C₆H₄NH₂I and CuCl₂ in N,N-dimethylformamide. Photoelectrochemical characteristics show that the C₆H₄NH₂CuCl₂I film demonstrated a stable photocurrent (∼1 μA/cm²) in an aqueous solution under white light (11.5 mW/cm²) even after 3000 s, while exhibiting a photon-to-current efficiency of 0.093% under AM1.5 (100 mW/cm²) illumination. However, these values were significantly lower than those of the CH₃NH₃PbX₃ (X = I, Cl) film in solid devices. The electron diffusion length L(e^-) (373 nm) and hole diffusion length L(h⁺) (177 nm) in the C₆H₄NH₂CuCl₂I photoelectrode were significantly lower than those of CH₃NH₃PbX₃, limiting the photoelectrochemical and photocatalysis performances. Moreover, L(h⁺) was shorter than L(e^-) in the C₆H₄NH₂CuCl₂I photoelectrode, resulting in the hole-collecting efficiency [η_c(h⁺)] being lower than the electron-collecting efficiency [η_c(e^-)]. A CuO interlayer was introduced as a hole transport layer for the C₆H₄NH₂CuCl₂I photoelectrode, which improved L(h⁺) and η_c(h⁺).

Interlocked 3D active carbon fibers and monolithic I-doped Bi2O2CO3 structure built by 2D face-to-face interaction: endowed with cycling stability and photocatalytic activity

Photocatalysis is considered a remarkable green method in the catalytic degradation of wastewater; however, the collection and loading of the powdered catalyst is still a problem.

Highly Efficient Visible-Light-Induced Photocatalytic Hydrogen Production via Water Splitting using FeCl3 -Based Ionic Liquids as Homogeneous Photocatalysts

The ionic liquid (IL) 1-octyl-3-methylimidazolium bromide/FeCl₃ [OMIM]Br/FeCl₃ was prepared with three molar ratios of [OMIM]Br/FeCl₃ (0.5 : 1, 1 : 1, and 2 : 1), and fully characterized through ¹ H and ¹³ C NMR, Fourier-transform IR, and Raman spectroscopic techniques. The optical properties of the prepared [OMIM]Br/FeCl₃ ILs were revealed via diffuse reflectance and photoluminescence spectra. The photocatalytic activity of [OMIM]Br/FeCl₃ ILs as homogenous photocatalysts were investigated towards hydrogen generation from methanol/water mixtures under visible light irradiation. The FeCl₃ -based IL with [OMIM]Br/FeCl₃ molar ratio of 1 : 1 exhibited the highest visible light photocatalytic activity with a hydrogen productivity of 243.2 mmol h^-1  g^-1 and a hydrogen purity of 95.5 %; such a high hydrogen yield and purity was reported for the first time. It was proposed that [OMIM] Br acted as an electron acceptor, which delayed the electron-hole pair recombination of FeCl₃ . Also, [OMIM] Br could capture the produced carbon dioxide that is released with hydrogen gas. Additionally, [OMIM] Br/FeCl₃ could be reused six times with nearly the same photocatalytic activity. These outstanding credits in terms of hydrogen generation rate and purity plus the economic feasibility, through several cycles of reuse, could certify such an IL as a promising photocatalyst for employment in water splitting. This paper suggests ways forward for research to develop the use of ILs as efficient and effective photocatalysts for hydrogen generation via water splitting.

The Photoluminescence and Biocompatibility of CuInS2-Based Ternary Quantum Dots and Their Biological Applications

Semiconductor quantum dots (QDs) have become a unique class of materials with great potential for applications in biomedical and optoelectronic devices. However, conventional QDs contains toxic heavy metals such as Pb, Cd and Hg. Hence, it is imperative to find an alternative material with similar optical properties and low cytotoxicity. Among these materials, CuInS2 (CIS) QDs have attracted a lot of interest due to their direct band gap in the infrared region, large optical absorption coefficient and low toxic composition. These factors make them a good material for biomedical application. This review starts with the origin and photophysical characteristics of CIS QDs. This is followed by various synthetic strategies, including synthesis in organic and aqueous solvents, and the tuning of their optical properties. Lastly, their significance in various biological applications is presented with their prospects in clinical applications.

Unique Luminescence of Hexagonal Dominant Colloidal Copper Indium Sulphide Quantum Dots in Dispersed Solutions

Luminescent hexagonal dominant copper indium sulphide (h-dominant CIS) quantum dots (QDs) by precursor-injection of mixed metal-dialkyldithiocarbamate precursors. Owing to the different reactivity of the precursors, this method allowed the CIS QDs to grow while retaining the crystallinity of the hexagonal nucleus. The photoluminescence (PL) spectra exhibited dual emission (600–700 nm red emission and 700–800 nm NIR emission) resulting from the combined contributions of the hexagonal (wurtzite) h-CIS and tetragonal (chalcopyrite) t-CIS QDs, i.e. the NIR and red emissions were due to the h-CIS QDs and coexisting t-CIS QDs (weight ratio of h-CIS/t-CIS ~ 10), respectively. The PL intensities of the h-CIS as well as t-CIS QDs were enhanced by post-synthetic heat treatment; the t-CIS QDs were particularly sensitive to the heat treatment. By separating h-CIS and t-CIS successfully, it was demonstrated that this phenomenon was not affected by size and composition but by the donor-acceptor pair states and defect concentration originating from their crystal structure. The h-dominant CIS QDs in this work provide a new technique to control the optical property of Cu-In-S ternary NCs.

The Effect of Cu and Ga Doped ZnIn2S4 under Visible Light on the High Generation of H2 Production

A Cu+ and Ga3+ co-doped ZnIn2S4 photocatalyst (Zn(1−2x)(CuGa)xIn2S4) with controlled band gap was prepared via a simple one-step solvothermal method. Zn(1−2x)(CuGa)xIn2S4 acted as an efficient photocatalyst for H2 evolution under visible light irradiation (λ > 420 nm; 4500 µW/cm2). The effects of the (Cu and Ga)/Zn molar ratios of Zn(1−2x)(CuGa)xIn2S4 on the crystal structure (hexagonal structure), morphology (microsphere-like flower), optical property (light harvesting activity and charge hole separation ability), and photocatalytic activity have been investigated in detail. The maximum H2 evolution rate (1650 µmol·h−1·g−1) was achieved over Zn0.84(CuGa)0.13In2S4, showing a 3.3 times higher rate than that of untreated ZnIn2S4. The bandgap energy of Zn(1−2x)(CuGa)xIn2S4 decreased from 2.67 to 1.90 eV as the amount of doping Cu+ and Ga3+ increased.

Optimization of CuIn1-XGaXS2 Nanoparticles and Their Application in the Hole-Transporting Layer of Highly Efficient and Stable Mixed-Halide Perovskite Solar Cells

Inorganic hole-transport materials (HTMs) have been frequently applied in perovskite solar cells (PSCs) and are a promising solution to improve the poor stability of PSCs. In this study, we investigate solution-processed copper indium gallium disulfide (CIGS) nanocrystals (NCs) as a dopant-free inorganic HTM in n-i-p type PSCs. Moreover, Cs_0.05(MA_0.17-FA_0.83)_0.95Pb(I_0.83Br_0.17)₃ mixed-halide perovskite with proper crystalline quality and long-time stability was utilized as the light-absorbing layer under ambient conditions. To optimize the cell performance and better charge extraction from the perovskite layer, the Ga concentration in the Cu(In_1-XGa_X)S₂ composition was changed, and the X value was altered between 0.0 and 0.75. It was shown that the CIGS band gap enhances with increasing Ga content; thus, with tunable band gaps and engineering of the energy level alignment, a better collection of photogenerated holes and a reduced electron-hole recombination rate could be achieved. The maximum power conversion efficiency of 15.6% was obtained for the PSC with Cu(In_0.5Ga_0.5)S₂ hole-transport layer composition, which is the highest efficiency reported so far for CIGS-based dopant-free PSCs. This value is very close to the efficiency of devices fabricated with doped spiro-OMeTAD as an organic HTM. Additionally, the stability of nonencapsulated PSCs was studied, and CIGS-based devices demonstrated 70% retention after 90 days of aging in the dark and in 50% relative humidity conditions. This result is quite better than the similar measurements for the doped spiro-OMeTAD-based devices.

Improvement of Photocatalytic H2-Generation under Visible Light Irradiation by Controlling the Band Gap of ZnIn2S4 with Cu and In

The band gap controlled photocatalyst (Zn0.74Cu0.13In2S3.805) was prepared via a simple one-step solvothermal method. The effects of doping of Cu+ and excess In on the photocatalytic activity of ZnIn2S4 photocatalyst were investigated. In addition, optical properties, surface morphology and crystal structure were evaluated. The maximum H2 evolution rate (2370 µmol h−1 g−1) was achieved with Zn0.74Cu0.13In2S3.805, which was about five times higher than that of untreated ZnIn2S4 under visible light (λ ≥ 420 nm). The band gap of Zn0.74Cu0.13In2S3.805 decreased to 1.98 eV by raising the maximum position of the valence band, compared to ZnIn2S4. Furthermore, the recombination of electron hole pairs was effectively reduced. This research contributes to the development of highly active photocatalysts under visible light.

Mechanochemical Synthesis and Characterization of CuInS₂/ZnS Nanocrystals

In this study, CuInS₂/ZnS nanocrystals were synthesized by a two-step mechanochemical synthesis for the first time. In the first step, tetragonal CuInS₂ was prepared from copper, indium and sulphur precursors. The obtained CuInS₂ was further co-milled with zinc acetate dihydrate and sodium sulphide nonahydrate as precursors for cubic ZnS. Structural characterization of the CuInS₂/ZnS nanocrystals was performed by X-ray diffraction analysis, Raman spectroscopy and transmission electron microscopy. Specific surface area of the product (86 m²/g) was measured by low-temperature nitrogen adsorption method and zeta potential of the particles dispersed in water was calculated from measurements of their electrophoretic mobility. Optical properties of the nanocrystals were determined using photoluminescence emission spectroscopy.

Ligand-free preparation of polymer/CuInS2 nanocrystal films and the influence of 1,3-benzenedithiol on their photovoltaic performance and charge recombination properties

Bulk heterojunction solar cells based on conjugated polymer donors and fullerene-derivative acceptors have received much attention in the last decade. Alternative acceptors like organic non-fullerene acceptors or inorganic nanocrystals have been investigated to a lesser extent; however, they also show great potential. In this study, one focus is set on the investigation of the in situ growth of copper indium sulfide nanocrystals in a conjugated polymer matrix. This preparation method allows the fabrication of a hybrid active layer without long-chain ligands, which could hinder charge separation and transport. In contrast, surfactants for the passivation of the nanocrystal surface are missing. To tackle this problem, we modified the absorber layer with 1,3-benzenedithiol and investigated the influence on charge transfer and solar cell performance. Using ToF-SIMS measurements, we could show that 1,3-benzenedithiol is successfully incorporated and homogeneously distributed in the absorber layer, which significantly increases the power conversion efficiency of the corresponding solar cells. This can be correlated to an improved charge transfer between the nanocrystals and the conjugated polymer as revealed by transient absorption spectroscopy as well as prolonged carrier lifetimes as disclosed by transient photovoltage measurements.

Optical Properties, Synthesis, and Potential Applications of Cu-Based Ternary or Quaternary Anisotropic Quantum Dots, Polytypic Nanocrystals, and Core/Shell Heterostructures

This review summaries the optical properties, recent progress in synthesis, and a range of applications of luminescent Cu-based ternary or quaternary quantum dots (QDs). We first present the unique optical properties of the Cu-based multicomponent QDs, regarding their emission mechanism, high photoluminescent quantum yields (PLQYs), size-dependent bandgap, composition-dependent bandgap, broad emission range, large Stokes’ shift, and long photoluminescent (PL) lifetimes. Huge progress has taken place in this area over the past years, via detailed experimenting and modelling, giving a much more complete understanding of these nanomaterials and enabling the means to control and therefore take full advantage of their important properties. We then fully explore the techniques to prepare the various types of Cu-based ternary or quaternary QDs (including anisotropic nanocrystals (NCs), polytypic NCs, and spherical, nanorod and tetrapod core/shell heterostructures) are introduced in subsequent sections. To date, various strategies have been employed to understand and control the QDs distinct and new morphologies, with the recent development of Cu-based nanorod and tetrapod structure synthesis highlighted. Next, we summarize a series of applications of these luminescent Cu-based anisotropic and core/shell heterostructures, covering luminescent solar concentrators (LSCs), bioimaging and light emitting diodes (LEDs). Finally, we provide perspectives on the overall current status, challenges, and future directions in this field. The confluence of advances in the synthesis, properties, and applications of these Cu-based QDs presents an important opportunity to a wide-range of fields and this piece gives the reader the knowledge to grasp these exciting developments.

Hot injection synthesis of CuInS2 nanocrystals using metal xanthates and their application in hybrid solar cells

Copper indium sulfide nanocrystals with sizes of 3–4 nm were synthesized from metal xanthates in a hot injection reaction. After ligand exchange, their performance as acceptors in polymer/nanocrystal hybrid solar cells was evaluated.

Controllable fabrication of α-Ag2WO4 nanorod-clusters with superior simulated sunlight photocatalytic performance

This work presents the greatly boosted photoactivity of α-Ag₂WO₄ nanorod-clusters fabricated by adjusting the molar ratio of raw materials.

Copper selenide (Cu3Se2 and Cu2-xSe) thin films: electrochemical deposition and electrocatalytic application in quantum dot-sensitized solar cells

In this work, high crystallinity copper selenide thin films directly deposited onto conducting substrates were obtained through a potentiostatic electrodeposition approach. The as-deposited copper selenides involve annealing induced phase transformation from tetragonal Cu3Se2 to cubic Cu2-xSe. The annealing also leads to a remarkable morphology change from dendritic nanosheets to connected networks and separated particle shapes for the annealed (A-Cu2-xSe) and selenized (S-Cu2-xSe) samples, respectively. The copper selenide thin films were demonstrated to serve as efficient counter electrodes (CEs) in quantum dot-sensitized solar cells (QDSCs) for electrocatalyzing polysulfide electrolyte regeneration. The CdS/CdSe QDSCs constructed with copper selenide CEs deliver considerable power conversion efficiencies (PCEs), especially an optimal value of 3.89% for the A-Cu2-xSe CE-based device. The enhanced photovoltaic performance benefits from the connected network microstructure of A-Cu2-xSe films which afford a large number of reaction sites and efficient charge transport pathways. The Tafel polarization characterization further indicates that, in contrast to the commonly used Cu2S and Pt CEs, the non-stoichiometric Cu2-xSe CE exhibits better electrochemical catalytic activity. This work highlights the great potential of electrodeposition for fabricating promising copper selenide CEs for high performance QDSCs.

Facile preparation and characterization of ZnCdS nanocrystals for interfacial applications in photovoltaic devices

Recently, ZnCdS nanocrystals (NCs) have attracted intense attention because of their specific optical properties and electrical characteristics. In this paper, a green and facile solution method is reported for the preparation of ZnCdS nanocrystals using dimethylsulfoxide as small molecular ligands. The ZnCdS nanocrystals are used as an interface modification material in the photovoltaic devices. It is found that the modification of ZnCdS on TiO₂ surface not only suppresses the recombination loss of carriers but also reduces the series resistance of TiO₂/active layer. Consequently, both of the short circuit current (J_sc) and the fill factor (FF) of the solar cells were significantly improved. Power conversion efficiency (PCE) of 7.75% based on TiO₂/ZnCdS was achieved in contrast to 6.65% of the reference devices based on pure TiO₂ film in organic solar cells. Furthermore, the PCE of perovskite solar cells based on TiO₂/ZnCdS was observed with 8.3% enhancement compared to that of pure TiO₂-based ones.

Hierarchical CuInS2-based heterostructure: Application for photocathodic bioanalysis of sarcosine

In this study, on the basis of hierarchical CuInS₂-based heterostructure, a novel cathodic photoelectrochemical (PEC) enzymatic bioanalysis of the sarcosine detection was reported. Specifically, heterostructured CuInS₂/NiO/ITO photocathode was prepared and sarcosine oxidases (SOx) were integrated for the construction of the enzymatic biosensor. In the bioanalysis, the O₂-dependent suppression of the cathodic photocurrent can be observed due to the competition between the as-fabricated O₂-sensitive photocathode and the SOx-catalytic event toward O₂ reduction. Based on the sarcosine-controlled O₂ concentration, a novel photocathodic enzymatic biosensor could be realized for the sensitive and specific sarcosine detection. This work manifested the great potential of CuInS₂-based heterostructure as a novel platform for future PEC bioanalytical development and also a PEC method for sarcosine detection, which could be easily extended to numerous other enzymatic systems and to our knowledge has not been reported. This work is expected to stimulate more interest in the design and implementation of numerous CuInS₂-based heterostructured photocathodic enzymatic sensing.

Effect of sulfonating agent and ligand chemistry on structural and optical properties of CuSbS2 particles prepared by heat-up method

CuSbS₂ particles were prepared by a facile heat-up method to investigate the effect of sulfur source and ligand chemistry.

On the phase control of CuInS2 nanoparticles from Cu-/In-xanthates

In this paper we report the synthesis characterisation of six In(iii) xanthate complexes that have been used for the synthesis of CuInS₂ nanoparticles in conjunction with a Cu(i)-xanthate – we have also demonstrated an ability to control the phase of the material through choice of solvent.

Ethanol–water ambient precipitation of {111} facets exposed Ag3PO4 tetrahedra and its hybrid with graphene oxide for outstanding photoactivity and stability

The work presents the combinative merits of {111} facet effect and the GO hybrid of Ag₃PO₄ photocatalyst with dramatically improved photocatalytic activity and admirable circulation runs for water treatment.

Comparative advantages of Zn–Cu–In–S alloy QDs in the construction of quantum dot-sensitized solar cells

Alloyed structures of quantum dot light-harvesting materials favor the suppression of unwanted charge recombination as well as acceleration of the charge extraction and therefore the improvement of photovoltaic performance of the resulting solar cell devices. Herein, the advantages of Zn–Cu–In–S (ZCIS) alloy QD serving as light-harvesting sensitizer materials in the construction of quantum dot-sensitized solar cells (QDSCs) were compared with core/shell structured CIS/ZnS, as well as pristine CIS QDs. The built QDSCs with alloyed Zn–Cu–In–S QDs as photosensitizer achieved an average power conversion efficiency (PCE) of 8.47% (V_oc = 0.613 V, J_sc = 22.62 mA cm⁻², FF = 0.610) under AM 1.5G one sun irradiation, which was enhanced by 21%, and 82% in comparison to those of CIS/ZnS, and CIS based solar cells, respectively. In comparison to cell device assembled by the plain CIS and core/shell structured CIS/ZnS, the enhanced photovoltaic performance in ZCIS QDSCs is mainly ascribed to the faster photon generated electron injection rate from QD into TiO₂ substrate, and the effective restraint of charge recombination, as confirmed by incident photon-to-current conversion efficiency (IPCE), open-circuit voltage decay (OCVD), as well as electrochemical impedance spectroscopy (EIS) measurements.

Benefiting from the accelerative electron injection and retarded charge recombination, Zn–Cu–In–S alloy QD based QDSC achieved a PCE of 8.55%, which is 21%, and 82% higher than those of CIS/ZnS, and pristine CIS QDs based solar cells, respectively.

Compound Copper Chalcogenide Nanocrystals

This review captures the synthesis, assembly, properties, and applications of copper chalcogenide NCs, which have achieved significant research interest in the last decade due to their compositional and structural versatility. The outstanding functional properties of these materials stems from the relationship between their band structure and defect concentration, including charge carrier concentration and electronic conductivity character, which consequently affects their optoelectronic, optical, and plasmonic properties. This, combined with several metastable crystal phases and stoichiometries and the low energy of formation of defects, makes the reproducible synthesis of these materials, with tunable parameters, remarkable. Further to this, the review captures the progress of the hierarchical assembly of these NCs, which bridges the link between their discrete and collective properties. Their ubiquitous application set has cross-cut energy conversion (photovoltaics, photocatalysis, thermoelectrics), energy storage (lithium-ion batteries, hydrogen generation), emissive materials (plasmonics, LEDs, biolabelling), sensors (electrochemical, biochemical), biomedical devices (magnetic resonance imaging, X-ray computer tomography), and medical therapies (photochemothermal therapies, immunotherapy, radiotherapy, and drug delivery). The confluence of advances in the synthesis, assembly, and application of these NCs in the past decade has the potential to significantly impact society, both economically and environmentally.

Synthetic strategies and biomedical applications of I–III–VI ternary quantum dots

In this review, we discuss recent advances of I–III–VI QDs with a major focus on synthesis and biomedical applications; advantages include low toxicity and fluorescent tuning in the biological window.

Preparation and photoluminescence properties of yellow-emitting CuInS2/ZnS quantum dots embedded in TMAS-derived silica

Photostable silica composites containing CuInS₂/ZnS/ZnS quantum dots were fabricated using a sol–gel method. Their photoluminescence quantum yields were 43–47%.

Aqueous synthesis of highly fluorescent and stable Cu–In–S/ZnS core/shell nanocrystals for cell imaging

An aqueous synthesis route has been presented to prepare hydrophilic Cu–In–S/ZnS core/shell nanocrystals with bright and stable fluorescence.

l-Cysteine assisted-synthesis of 3D In2S3 for 3D CuInS2 and its application in hybrid solar cells

Hierarchical CuInS₂ is synthesized with hierarchical In₂S₃ as the template, which is applied in MEH-PPV/CuInS₂ hybrid solar cells firstly.

Aggregation-induced emission properties of hydrothermally synthesized Cu–In–S quantum dots

This article reports water-soluble Cu–In–S QDs with aggregation-induced emission (AIE) properties that can be induced by both an organic solvent and cations.

Optoelectronic Properties of CuInS2 Nanocrystals and Their Origin

The capacity of fluorescent colloidal semiconductor nanocrystals for commercial application has led to the development of nanocrystals with nontoxic constituent elements as replacements for the currently available Cd- and Pb-containing systems. CuInS2 is a good candidate material because of its direct band gap in the near-infrared spectral region and large optical absorption coefficient. The ternary nature, flexible stoichiometry, and different crystal structures of CuInS2 lead to a range of optoelectronic properties, which have been challenging to elucidate. In this Perspective, the optoelectronic properties of CuInS2 nanocrystals are described and what is known of their origin is discussed. We begin with an overview of their synthesis, structure, and mechanism of formation. A complete discussion of the tunable luminescence properties and the radiative decay mechanism of this system is then presented. Finally, progress toward application of these "green" nanocrystals is summarized.

Phase transformations of novel CuxS nanostructures as highly efficient counter electrodes for stable and reproducible quantum dot-sensitized solar cells

A quantum dot-sensitized solar cell assembled with a Cu_1.12S nanosphere counter electrode exhibited a high power conversion efficiency of 5.88%.

Room temperature synthesis of CuInS2 nanocrystals

Herein, we investigate a synthetic approach to prepare copper indium sulfide nanocrystals at room temperature.

Inorganic dye-sensitized solar cell employing In-enriched Cu–In–S ternary colloids prepared in water media

Inorganic dye-sensitized solar cells employing In-enriched Cu–In–S ternary colloids prepared in water exhibit high PCE at 3.54%.

Air-exposing microwave-assisted synthesis of CuInS2/ZnS quantum dots for silicon solar cells with enhanced photovoltaic performance

CIS/ZnS QDs were synthesized by microwave irradiation in air. The fabricated QDs/PMMA composite films were first applied to Si solar cells to improve the conversion efficiency by 3.8%.

Cu2ZnSnS4 quantum dots as effective electron acceptors for hybrid solar cells with a broad spectral response

Cu₂ZnSnS₄ quantum dots are synthesized by a facile solvothermal technique and used as a novel effective acceptor material for polymer-based hybrid solar cells with a broad spectral response.