Solution-Processed Sb2Se3 on TiO2 Thin Films Toward Oxidation- and Moisture-Resistant, Self-Powered Photodetectors

Recent Advances in Antimony Selenide Photodetectors

Photodetectors (PDs) rapidly capture optical signals and convert them into electrical signals, making them indispensable in a variety of applications including imaging, optical communication, remote sensing, and biological detection. Recently, antimony selenide (Sb2Se3) has achieved remarkable progress due to its earth-abundant, low toxicity, low price, suitable bandgap width, high absorption coefficient, and unique structural characteristics. Sb2Se3 has been extensively studied in solar cells, but there's a lack of timely updates in the field of PDs. A literature review based on Sb2Se3 PDs is urgently warranted. This review aims to provide a concise understanding of the latest progress in Sb2Se3 PDs, with a focus on the basic characteristics and the performance optimization for Sb2Se3 photoconductive-type and photodiode-type detectors, including nanostructure regulation, process optimization, and stability improvement of flexible devices. Furthermore, the application progresses of Sb2Se3 PDs in heart rate monitoring, and monolithic-integrated matrix images are introduced. Finally, this review presents various strategies with potential and feasibility to address challenges for the rapid development and commercial application of Sb2Se3 PDs.

Controlled Epitaxial Growth of (hk1)-Sb2Se3 Film on Cu9S5 Single Crystal via Post-Annealing Treatment for Photodetection Application

Antimony selenide (Sb2Se3) is a promising semiconductor for photodetector applications due to its unique photovoltaic properties. Achieving optimal carrier transport in (001)-Sb2Se3 by the material of contacting substrate requires in-depth study. In this paper, the induced growth of Sb2Se3 films from (hk0) to (hk1) planes is achieved on digenite (Cu9S5) films by post-annealing treatment. The flake-like and flower-like morphologies on the surface of Sb2Se3 films are caused by different thicknesses of the Cu9S5 films, which are related to the (hk0) and (hk1) planes of Sb2Se3 surface. The epitaxial growth of Sb2Se3 films on (105)-Cu9S5 surfaces exhibits thickness dependence. The results inform research into the controlled induced growth of low-dimensional materials. The device of Sb2Se3/Cu9S5/Si has good broadband response (visible to near-infrared), self-powered characteristics, and stability. As the crystalline quality of the Sb2Se3 film increases along the (hk1) plane, the carrier transport is enhanced correspondingly. Under the 980 nm light irradiation, the device has an excellent switching ratio of 2 × 104 at 0 bias, with responsivity, detectivity, and response time up to 17 µA W-1, 1.48 × 107 Jones, and 355/490 µs, respectively. This suggests that Sb2Se3 is suitable for self-powered photodetectors and related optical and optoelectronic devices.

Polymeric viologen-based electron transfer mediator for improving the photoelectrochemical water splitting on Sb2Se3 photocathode

The photogenerated charge carrier separation and transportation of inside photocathodes can greatly influence the performance of photoelectrochemical (PEC) H2 production devices. Coupling TiO2 with p-type semiconductors to construct heterojunction structures is one of the most widely used strategies to facilitate charge separation and transportation. However, the band position of TiO2 could not perfectly match with all p-type semiconductors. Here, taking antimony selenide (Sb2Se3) as an example, a rational strategy was developed by introducing a viologen electron transfer mediator (ETM) containing polymeric film (poly-1,1'-dially-[4,4'-bipyridine]-1,1'-diium, denoted as PV2+) at the interface between Sb2Se3 and TiO2 to regulate the energy band alignment, which could inhibit the recombination of photogenerated charge carriers of interfaces. With Pt as a catalyst, the constructed Sb2Se3/PV2+/TiO2/Pt photocathode showed a superior PEC hydrogen generation activity with a photocurrent density of -18.6 mA cm-2 vs. a reversible hydrogen electrode (RHE) and a half-cell solar-to-hydrogen efficiency (HC-STH) of 1.54% at 0.17 V vs. RHE, which was much better than that of the related Sb2Se3/TiO2/Pt photocathode without PV2+ (-9.8 mA cm-2, 0.51% at 0.10 V vs. RHE).

Solution-Processed Sb2S3-Based Heterojunction for Self-Powered Broad Band Weak Light Detection

Antimony sulfide (Sb2S3) has recently regained the attention of photovoltaic researchers as a promising solar absorber; however, its application for the detection of white light remains relatively unexplored. Herein, we report on the self-powered heterojunction photodetector based on a device-grade Sb2S3 film made at low temperature with solution processing. The Sb2S3 absorber film was prepared by single-step spin coating of a novel precursor ink using antimony trichloride as the antimony source along with the low melting thioacetamide as the sulfur source in 2-methoxyethanol, a low boiling environmentally friendly solvent. A simple TiO2/Sb2S3 heterojunction device made by using the film shows a power conversion efficiency of 1.22% without any hole transporting layer. Interestingly, the self-powered photodetector performance of the device under white light exhibits a high on/off ratio of 2.2 × 104 under 1 sun illumination. Moreover, this optical filter-free ultraviolet-visible absorbing near-infrared blind photodetector is equally capable of detecting both strong and weak white light, with a response time of 98 ms. Further, an example of the real-life application of the device is successfully demonstrated by constructing a weak light-detecting sunlight tracking system.

High-performance visible-near-infrared photodetector based on the N2200/Sb2Se3 nanorod arrays organic-inorganic hybrid heterostructure

Antimony selenide (Sb2Se3) is a suitable candidate for a broadband photodetector owing to its remarkable optoelectronic properties. Achieving a high-performance self-powered photodetector through a desirable heterojunction still needs more efforts to explore. In this work, we demonstrate a broadband photodetector based on the hybrid heterostructure of Sb2Se3 nanorod arrays (NRAs) absorber and polymer acceptor (P(NDI2OD-T2), N2200). Owing to the well-matched energy levels between N2200 and Sb2Se3, the recombination of photogenerated electrons and holes in N2200/Sb2Se3 hybrid heterostructure is greatly inhibited. The photodetector can detect the wavelength from 405 to 980 nm, and exhibit high responsivity of 0.39 A/W and specific detectivity of 1.84 × 1011 Jones at 780 nm without bias voltage. Meanwhile, ultrafast response rise time (0.25 ms) and fall time (0.35 ms) are obtained. Moreover, the time-dependent photocurrent of this heterostructure-based photodetector keeps almost the same value after the storge for 40 days, indicating the excellent stability and reproducibility. These results demonstrate the potential application of a N2200/Sb2Se3 NRAs heterojunction in visible-near-infrared photodetectors.

Application of Nanostructured TiO2 in UV Photodetectors: A Review

As a wide-bandgap semiconductor material, titanium dioxide (TiO₂ ), which possesses three crystal polymorphs (i.e., rutile, anatase, and brookite), has gained tremendous attention as a cutting-edge material for application in the environment and energy fields. Based on the strong attractiveness from its advantages such as high stability, excellent photoelectric properties, and low-cost fabrication, the construction of high-performance photodetectors (PDs) based on TiO₂ nanostructures is being extensively developed. An elaborate microtopography and device configuration is the most widely used strategy to achieve efficient TiO₂ -based PDs with high photoelectric performances; however, a deep understanding of all the key parameters that influence the behavior of photon-generated carriers, is also highly required to achieve improved photoelectric performances, as well as their ultimate functional applications. Herein, an in-depth illustration of the electrical and optical properties of TiO₂ nanostructures in addition to the advances in the technological issues such as preparation, microdefects, p-type doping, bandgap engineering, heterojunctions, and functional applications are presented. Finally, a future outlook for TiO₂ -based PDs, particularly that of further functional applications is provided. This work will systematically illustrate the fundamentals of TiO₂ and shed light on the preparation of more efficient TiO₂ nanostructures and heterojunctions for future photoelectric applications.

Underwater Multispectral Computational Imaging Based on a Broadband Water-Resistant Sb2Se3 Heterojunction Photodetector

Exploration, utilization, and protection of marine resources are of great significance to the survival and development of mankind. However, currently classical optical cameras suffer information loss, low contrast, and color distortion due to the absorption and scattering nature for the underwater environment. Here, we demonstrate an underwater multispectral computational imaging system combined with single-photodetector imaging algorithm technology and a CdS/Sb₂Se₃ heterojunction photodetector. The computational imaging technology coupled with an advanced Fourier algorithm can capture a scene by a single photodetector without spatial resolution that avoids the need to rely on high-density detectors array and bulky optical components in traditional imaging systems. This convenient computational imaging method provides more flexible possibilities for underwater imaging and promises to give more imaging capabilities (such as multispectral imaging, antiscattering imaging capability) to meet ever-changing demand of underwater imaging. In addition, the water-resistant CdS/Sb₂Se₃ heterojunction photodetector fabricated by the close spaced sublimation (Sb₂Se₃) and chemical bath deposition (CdS) shows excellent self-powered photodetection performance at zero bias with high LDR of 128 dB, broadband response spectrum range of 300-1050 nm, high responsivity up to 0.47 A/W, and high specific detectivity over 5 × 10¹² jones. Compared with the traditional optical imaging system, our designed computational imaging system that combines the advanced Fourier algorithm and a high-performance CdS/Sb₂Se₃ heterojunction photodetector exhibits outstanding antiscattering imaging capability (shielded by frosted glass), weak light imaging capability (∼0.2 μW/cm², corresponding to moonlight intensity), and multispectral imaging capability. Therefore, we believe that this work will boost the progress of marine science.

A transparent, self-powered photodetector based on p-CuI/n-TiO2heterojunction film with high on-off ratio

Ultraviolet(UV) photodetectors(PDs) can monitor UV radiation, enabling it to be effective for many applications, such as communication, imaging and sensing. The rapid progress on portable and wearable optoelectronic devices places a great demand on self-powered PDs. However, high-performance self-powered PDs are still limited. Herein we display a transparent and self-powered PD based on a p-CuI/n-TiO₂heterojunction, which exhibits a high on-off ratio (∼10⁴at 310 nm) and a fast response speed (rise time/decay time = 0.11 ms/0.72 ms) without bias. Moreover, the device shows an excellent UV-selective sensitivity as a solar-blind UV PD with a high UV/visible rejection ratio (R_{300 nm}/R_{400 nm}= 5.3 × 10²), which can be ascribed to the wide bandgaps of CuI and TiO₂. This work provides a feasible route for the construction of transparent, self-powered PDs based on p-n heterojunctions.

High-responsivity, self-driven visible-near infrared Sb2Se3 nanorod array photodetector

Anisotropic antimony selenide (Sb₂Se₃) semiconductor has received considerable attention due to its unique one-dimensional crystal structure and corresponding superior and anisotropic optical and electronic properties. It is a promising material for a wide range of applications related to electronics and optoelectronics. Herein, we demonstrate a high-performance and self-powered Sb₂Se₃ nanorod array-based core/shell heterojunction detector fabricated on glass substate. The detector shows a wide spectral photoresponse range from visible to near-infrared (405-980 nm). The detector yields a detectivity of as high as 2.06×10¹² Jones in the visible light (638 nm) and that of 1.82×10¹² Jones (830 nm) at zero bias. Due to the strong built-in filed and excellent carrier transport, the detector exhibits ultrafast response speed at both rise (30 μs) and decay (68 μs) processes. Further analysis demonstrates that the noise is mainly generated from the 1/f noise in the low frequency range, while it is affected by the shot noise and generation-recombination noise in high frequency.

Ultrafast Speed, Dark Current Suppression, and Self-Powered Enhancement in TiO2-Based Ultraviolet Photodetectors by Organic Layers and Ag Nanowires Regulation

TiO₂-based photodetectors (PDs) have been hotspots in recent years for their excellent thermal stabilities and optoelectronic performance under ultraviolet (UV) light. However, the high dark current caused by defects in TiO₂ films has limited the detectivity (D) of these PDs. Here, the dark current of a TiO₂-based PD was effectively reduced by 3 magnitudes (from 0.1 mA to 20 nA) and D was increased to 1.2 × 10¹⁴ Jones by introducing PC71BM. The TiO₂/PC71BM heterojunction also made the PD self-powered, and by further introducing an interface layer of PEDOT:PSS and finely optimizing the electrode Ag nanowires (Ag NWs), the self-powered responsivity (R) was increased to 33 mA/W. Ultrafast rise/decay times (129 ns/1 ms at -1 V and 0.06 s/<1 μs at 0 V) were achieved. This work successfully applied an organic-inorganic heterojunction, an organic interface, and Ag NWs to suppress the dark current and enhance the self-powered photocurrent/R of inorganic PDs, providing a feasible strategy in high-performance UV PDs' design.

Oleic acid-induced, controllable surface oxidation to enhance the photoresponse performance of Sb2Se3 nanorods

The surface oxidation level of Sb₂Se₃ nanorods is tunable by varying the volume ratio of oleic acid during the synthesis and a modest oxidation level (20–30%) is found to be favorable for the optoelectronic properties of Sb₂Se₃.