ZnO@SnO2 engineered composite photoanodes for dye sensitized solar cells

Dye-Sensitized Solar Cell for Building-Integrated Photovoltaic (BIPV) Applications

One of the important research directions in the field of photovoltaics is integration with construction. The integration of solar cell systems with a building can reduce installation costs and help optimize the used space. Among the few literature reports on photovoltaic roof tiles, solutions with silicon and thin film solar cells dominate. An interesting solution may be the application of dye-sensitized solar cells. In addition to their interesting properties, they also have aesthetic value. In the classic arrangement, they are constructed using glass with a transparent conductive layer (TCL). This article describes replacing a classic glass counter electrode with an electrode based on a ceramic tile and nickel foil. First, a continuous and homogeneous fluorine-doped tin oxide (FTO) thin film was developed so that the above-mentioned substrate could be applied. The atomization method was used for this purpose. Then, nanocolloidal platinum paste was deposited as a catalytic material using the screen printing method. The electrical parameters of the manufactured DSSCs with and without a counter electrode tile were characterized by measuring their current–voltage characteristics under standard AM 1.5 radiation. A dye-sensitized solar cell integrated with ceramic tiles and nickel foil was produced and displayed an efficiency of over 4%. This solution makes it possible to expand their construction applications. The advantage of this solution is full integration with construction, while simultaneously generating electricity. A dye-sensitized solar cell was built layer-by-layer on a ceramic tile and nickel foil.

Zinc phthalocyanines as light harvesters for SnO2-based solar cells: a case study

SnO₂ nanoparticles have been synthesized and used as electron transport material (ETM) in dye sensitized solar cells (DSSCs), featuring two peripherally substituted push-pull zinc phthalocyanines (ZnPcs) bearing electron donating diphenylamine substituents and carboxylic acid anchoring groups as light harvesters. These complexes were designed on the base of previous computational studies suggesting that the integration of secondary amines as donor groups in the structure of unsymmetrical ZnPcs might enhance photovoltaics performances of DSSCs. In the case of TiO₂-based devices, this hypothesis has been recently questioned by experimental results. Herein we show that the same holds for SnO₂, despite the optimal matching of the optoelectronic characteristics of the synthesized nanoparticles and diphenylamino-substituted ZnPcs, thus confirming that other parameters heavily affect the solar cells performances and should be carefully taken into account when designing materials for photovoltaic applications.

Tin-zinc-oxide nanocomposites (SZO) as promising electron transport layers for efficient and stable perovskite solar cells

Tin-zinc-oxide nanocomposites (SZO) with various Sn : Zn ratios were successfully fabricated and tested as electron transport layers (ETLs) in perovskite solar cells (PVSCs). The fabricated nanocomposites showed good crystallinity, good contact between layers, good electrical conductivity, and favorable light absorption, resulting in an enhancement in the net efficiency of CH3NH3PbI3 (MAPI)-based perovskite solar cells. The device made of SZO-Sn0.05 as an ETL showed a maximum power conversion efficiency (PCE) of 17.81% with a short-circuit current density (J sc) of 23.59 mA cm-2, an open-circuit voltage (V oc) of 1 V, and a fill factor (FF) of 0.754. However, the ETL containing lower Sn ratios showed PCEs of 12.02, 13.80 and 15.86% for pure ZnO, SZO-Sn0.2 and SZO-Sn0.1, respectively. Meanwhile, the reproducibility of 30 fabricated devices proved the outstanding long-term stability of the cells based on SZO nanocomposites, retaining ≈85% of their PCE over 1200 h of operation. In addition, the incident-photon-to-current efficiency (IPCE) exceeded 90% over the entire wavelength range from 400 to 800 nm. The enhancement in the PCE of the fabricated PVSCs can be ascribed to the large surface area of the SZO nanoparticles, high charge extraction efficiency, and suppression of charge recombination provided by SnO x . The current results suggest that our synthesized tin-zinc-oxide nanocomposite is an effective electron transport layer for efficient and stable perovskite solar cells.

Efficient Energy Harvesting in SnO2-Based Dye-Sensitized Solar Cells Utilizing Nano-Amassed Mesoporous Zinc Oxide Hollow Microspheres as Synergy Boosters

Finding the material characteristics satisfying most of the photovoltaic conditions is difficult. In contrast, utilization of foreign materials that can contribute to light harvesting and charge transfers in the devices is now desirable/thought-provoking. Herein, a binary hybrid photoanode utilizing nano-amassed micron-sized mesoporous zinc oxide hollow spheres (meso-ZnO HS) in conjunction with SnO₂ nanoparticles (NPs), i.e., SnO₂ NP_ZnO HS (for an optimized weight ratio (8:2)), displayed a nearly ∼4-fold increase in the efficiency (η) compared to that of bare SnO₂ nanoparticle device. Enhanced device efficacy in the composite photoanode-based device can be accredited to the dual function of nano-amassed meso-ZnO HS. Nano-amassed micron-sized ZnO HS embedded in the photoanode can increase the light-harnessing capability without sacrificing the surface area as well as optical confinement of light by multiple reflections within its cavity and enhanced light-scattering effects. Electrochemical impedance spectroscopy analysis revealed an extended lifetime of electron (τ_e) and a higher value of R _ct2 at the working electrode/dye/redox mediator interface, indicating a minimum photoinduced electron interception. The open-circuit voltage decay reveals a slower recombination kinetics of photogenerated electrons, supporting our claim that the nano-ammased meso-ZnO HS can serve as an energy barrier to the photoinjected electrons to retard the back-transfer to the electrolyte. Moreover, the improvement in the fill factors of the composite-based devices is endorsed to the facile penetration of the electrolyte through the pores of nano-amassed meso-ZnO HS, which increases the regeneration probability of oxidized dyes.

Porous SnO2 nanoparticles based ion chromatographic determination of non-fluorescent antibiotic (chloramphenicol) in complex samples

Nowadays, there are rising concerns about the extensive use of the antibiotics such as chloramphenicol (CAP), has threatened the human life in the form of various vicious diseases. The limited selectivity and sensitivity of confirmatory techniques (UV and electrochemical) and non-fluorescence property of CAP make its determination a challenging task in the modern pharmaceutical analysis. In order to redeem the selective, sensitive and cost-effective fluorescence methodology, here by the dual role of synthesized porous SnO2 nanoparticles were exploited; (i) a porous sorbent in a µ-QuEChERS based sample preparation and as (ii) a stimulant for the transformation of non-fluorescent analytes namely CAP and p-nitrophenol (p-NP) into their respective fluorescent product. We report a green, simple, selective and cost effective ion chromatographic method for CAP sensitive determination in three complex matrices including milk, human urine and serum. The synthesized sorbent not only selectively adsorbed and degraded the matrix/interferences but also selectively reduced the non-fluorescent antibiotic CAP into a fluorescent species. This developed ion chromatographic method exhibited good selectivity, linearity (r2 ≥ 0.996) and limit of detection (LOD) was in the range 0.0201-0.0280 µg/kg. The inter- and intraday precisions were also satisfactory having a relative standard deviation (RSDs) less than 14.96% and excellent recoveries of CAP in the range of 78.3-100.2% were retrieved in various complex samples.

Solid-state dye-sensitized solar cells based on Zn1-x Sn x O nanocomposite photoanodes

Solid-state dye-sensitized solar cells (ss-DSSCs) comprising Sn2+-substituted ZnO nanopowder were purposefully tailored via a co-precipitation method. The solar cells assembled in this work were sensitized with N719 ruthenium dye and insinuated with spiro-OMeTAD as a solid hole transport layer (HTL). Evidently, significant enhancement in cell efficiency was accomplished with Sn2+ ions-substituted ZnO photoelectrodes by maintaining the weight ratio of SnO at 5%. The overall power conversion efficiency was improved from 3.0% for the cell with pure ZnO to 4.3% for the cell with 5% SnO substitution. The improvement in the cell efficiency with Sn2+-substituted ZnO photoelectrodes is attributed to the considerably large surface area of the nanopowders for dye adsorption, efficient charge separation and the suppression of charge recombination provided by SnO. Furthermore, the energy distinction between the conduction band edges of SnO and ZnO implied a type II band alignment. Moreover, the durability as well as the stability of 15 assembled cells were studied to show the outstanding long-term stability of the devices made of Sn2+ ion substituted ZnO, and the PCE of each cell remained stable and ∼96% of its primary value was retained for up to 100 h. Subsequently, the efficacy was drastically reduced to ∼35% after 250 h of storage.

Nanoarchitectures in dye-sensitized solar cells: metal oxides, oxide perovskites and carbon-based materials

Dye-sensitized solar cells (DSSCs) have aroused great interest and been regarded as a potential renewable energy resource among the third-generation solar cell technologies to fulfill the 21^st century global energy demand. DSSCs have notable advantages such as low cost, easy fabrication process and being eco-friendly in nature. The progress of DSSCs over the last 20 years has been nearly constant due to some limitations, like poor long-term stability, narrow absorption spectrum, charge carrier transportation and collection losses and poor charge transfer mechanism for regeneration of dye molecules. The main challenge for the scientific community is to improve the performance of DSSCs by using different approaches, like finding new electrode materials with suitable nanoarchitectures, dyes in composition with promising semiconductors and metal quantum dot fluorescent dyes, and cost-effective hole transporting materials (HTMs). This review focuses on DSSC photo-physics, which includes charge separation, effective transportation, collection and recombination processes. Different nanostructured materials, including metal oxides, oxide perovskites and carbon-based composites, have been studied for photoanodes, and counter electrodes, which are crucial to achieve DSSC devices with higher efficiency and better stability.

Understanding the role of silica nanospheres with their light scattering and energy barrier properties in enhancing the photovoltaic performance of ZnO based solar cells

The present study discusses the design and development of a dye sensitized solar cell (DSSC) using a hybrid composite of ZnO nanoparticles (ZnO NP) and silica nanospheres (SiO₂ NS). A ≈22% enhancement in the overall power conversion efficiency (PCE, η) was observed for the device fabricated with a binary hybrid composite of 1 wt% SiO₂ NS and ZnO NP compared to the pristine ZnO NP device. A systematic investigation revealed the dual function of the silica nanospheres in enhancing the device efficacy compared to the bare ZnO NP based device. Sub-micron sized SiO₂ NS can boost the light harvesting efficiency of the photoanode by optical confinement, resulting in increased propagation length of the incident light by multiple internal reflections, which was confirmed by UV-Vis diffused reflectance spectroscopy. Electrochemical impedance spectroscopic (EIS) analysis showed a reduced recombination of photo-generated electrons to the I^-/I₃^- redox shuttle in the case of the composite photoanode. The higher recombination resistance (R_ct) in the case of a 1 wt% composite indicates that the SiO₂ NS serves as a partial energy barrier layer to retard the interfacial recombination (back transfer) of photo-generated electrons at the working electrode/electrolyte interface, increasing the device efficiency.

Novel Photoanode for Dye-Sensitized Solar Cells with Enhanced Light-Harvesting and Electron-Collection Efficiency

A novel photoanode structure modified by porous flowerlike CeO2 microspheres as a scattering layer with a thin TiO2 film deposited by atomic layer deposition (ALD) is prepared to achieve a significantly enhanced performance of dye-sensitized solar cells (DSSCs). The light scattering capability of the photoanode with the porous CeO2 microsphere layer is considerably improved. The interconnection of particles and electrical contact between bilayer and conducting substrate is further enhanced by an ALD-deposited TiO2 film, which effectively reduces the electron recombination and facilitates electron transport and thus enhances the charge collection efficiency of DSSCs. As a result, the overall efficiency of the obtained TiO2-CeO2-based cells reaches 9.86%, which is 31% higher than that of the DSSCs with a conventional TiO2 photoanode.

Direct observation of electronic transition–plasmon coupling for enhanced electron injection in dye-sensitized solar cells

We illustrate experimental evidence of the effect of surface plasmon resonance (SPR) of a noble metal on the ultrafast-electron injection efficiencies of a sensitizing dye in proximity of a wide band gap semiconductor.