CuSbS2 thin films by rapid thermal processing of Sb2S3-Cu stack layers for photovoltaic application

The earth-abundant material CuSbS2 (CAS) has shown good optical properties as a photovoltaic solar absorber material, but has seen relatively poor solar cell performance. To investigate the reason for this anomaly, the core levels of the constituent elements, surface contaminants, ionization potential, and valence-band spectra are studied by X-ray photoemission spectroscopy. The ionization potential and electron affinity for this material (4.98 and 3.43 eV) are lower than those for other common absorbers, including CuInxGa(1–x)Se2 (CIGS). Experimentally corroborated density functional theory (DFT) calculations show that the valence band maximum is raised by the lone pair electrons from the antimony cations contributing additional states when compared with indium or gallium cations in CIGS. The resulting conduction band misalignment with CdS is a reason for the poor performance of cells incorporating a CAS/CdS heterojunction, supporting the idea that using a cell design analogous to CIGS is unhelpful. Thes...

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Core Levels, Band Alignments, and Valence-Band States in CuSbS2 for Solar Cell Applications.

Solution processing is a practical low-cost strategy for depositing semiconductor thin films. A binary thiol–amine solvent mixture dissolves bulk Cu2S and Sb2S3 under ambient conditions, allowing for solution deposition and low temperature recovery of CuSbS2. The resulting films of earth abundant CuSbS2 possess optoelectronic properties suitable for photovoltaic applications.

Earth abundant CuSbS2 thin films solution processed from thiol–amine mixtures

The ternary Cu-Sb- and Cu-Bi-chalcogenides present a rich range of compounds of potential use for large-scale photovoltaics from Earth abundant elements. This paper reviews the state of fundamental knowledge about them, and their technological status with regard to solar cells. Research targets and missing data are highlighted, which may provide opportunities to help realize the goal of sustainable photovoltaics. The family of ternary Cu-Sb- and Cu-Bi-chalcogenides and their solid solutions present a rich selection of potential candidates for Earth-abundant low toxicity photovoltaic (PV) absorber materials. Moreover, they have some novel features imparted by the ns2 lone pair of electrons on the Sb and Bi ions. This review evaluates them as electronic materials, including experimental and theoretical evaluations of their phases, thermodynamic stability, point defects, conductivity, optical data, and PV performances. Formation of the materials in bulk, thin film, and nanoforms and the properties of the materials are critically assessed with relevance to their suitability for PV devices. There is special emphasis on CuSbS2 and CuSbSe2 which form the mainstay of the device literature and provide the most insights into the present-day limitation of the device efficiencies to 3 or 4%. Missing features of the literature are highlighted and clear statements recommending potential research pathways are made, which may help advance the technological performance from its present stuck position.

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Copper—antimony and copper—bismuth chalcogenides—Research opportunities and review for solar photovoltaics

Ternary chalcostibite copper antimony sulfide (CuSbS2) is an emerging semiconductor material having applications in photovoltaics, energy storage and optoelectronics due to its high absorption coefficient, suitable bandgap, and it consists of non-toxic and earth abundant elements CuSbS2 thin films are prepared by combining chemical bath deposition (antimony sulfide (Sb2S3)) and thermal evaporation (copper (Cu)) followed by a heat treatment and their application as visible to near infrared photodetectors is reported Crystalline structure, elemental composition, chemical state, morphology and optoelectronic properties of the films were characterized by various techniques The effect of three different Cu thicknesses (CAS 20, CAS 30 and CAS 40 nm) on the photodetection properties are evaluated under illumination using light emitting diodes (LEDs) and a laser The photodetectors fabricated are successfully tested under different wavelengths, power densities and applied voltage and their photoresponse cyclic stability for each wavelength of illumination was recorded From the sensitivity calculations, the sample with 20 nm Cu thickness (CAS 20) showed higher detection sensitivity for visible to near infrared wavelengths Better responsivity results were obtained for CAS 40 because of its improved crystallinity and phase purity Photodetector properties such as sensitivity and responsivity are evaluated for all the samples These results are beneficial for cost effective and environment friendly photodetectors and optoelectronic devices based on CuSbS2 thin films

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Copper antimony sulfide thin films for visible to near infrared photodetector applications

Copper antimony sulfide (CuSbS2) thin films have been gained interest recently as an emerging light absorbing material for photovoltaic applications. In this work we report synthesis and characterization of spray pyrolised CuSbS2 thin films. The precursor solution consisted of SbCl3, CuCl2 and NH2CSNH2 dissolved ethanol. The substrate temperature was kept at 200 °C. Samples were prepared at different molar ratios of Cu:Sb:S. These thin films were characterized using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, UV-visible spectroscopy, photocurrent and Hall effect measurements. P-type CuSbS2 thin films of orthorhombic structure were formed and the films showed photocurrent response. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Jose Agustin Ramos Aquino

Papers

Spray pyrolysed thin films of copper antimony sulfide as photovoltaic absorber