CuSbS₂ as a Promising Earth-Abundant Photovoltaic Absorber Material: A Combined Theoretical and Experimental Study

Abstract

Recently, CuSbS 2 has been proposed as an alternative earth-abundant absorber material for thin film solar cells. However, no systematic study on the chemical, optical, and electrical properties of CuSbS 2 has been reported. Using density functional theory (DFT) calculations, we showed that CuSbS 2 has superior defect physics with extremely low concentration of recombination-center defects within the forbidden gap, espeically under the S rich condition. It has intrinsically p-type conductivity, which is determined by the dominant Cu vacancy (V Cu ) defects with the a shallow ionization level and the lowest formation energy. Using a hydrazine based solution process, phase-pure, highly crystalline CuSbS 2 film with large grain size was successfully obtained. Optical absorption investigation revealed that our CuSbS 2 has a direct band gap of 1.4 eV. Ultraviolet photoelectron spectroscopy (UPS) study showed that the conduction band and valence band are located at 3.85 eV and −5.25 eV relative to the vacuum level, respectively. As the calculations predicted, a p-type conductivity is observed in the Hall effect measurements with a hole concentration of ∼10 18 cm −3 and hole mobility of 49 cm 2 /(V s). Finally, we have built a prototype FTO/CuSbS 2 /CdS/ZnO/ZnO:Al/Au solar cell and achieved 0.50% solar conversion efficiency. Our theoretical and experimental investigation confirmed that CuSbS 2 is indeed a very promising absorber material for solar cell application.

Characterization of Cu3SbS3 thin films grown by thermally diffusing Cu2S and Sb2S3 layers

“…7 (c) the range for S in sulphide phases [37]. All the corresponding binding energy values of the elements of Cu3SbS3 were found consistent with those in the literature [3,17,38].…”

“…In the literature, fabrication of the copper antimony sulfide thin films are found using both physical and chemical deposition techniques such has thermal evaporation [13][14][15], thermal diffusion [16], spin coating [17], chemical bath deposition [18], spray pyrolysis [19], electrochemical deposition [20,21] and hybrid inks method [22], etc. For example, Rabhi et al reported the copper antimony sulfide films fabricated via a thermal evaporation technique [13,14].…”

CuSbSe2 as a Potential Photovoltaic Absorber Material: Studies from Theory to Experiment

“…Since all low-energy defects have shallow levels (especially under Se-rich condition), CuSbSe 2 semiconductor can be considered as a good solar cell absorber free of recombination-center defects, similar to CuSbS 2 . [ 19 ] In brief, DFT calculations indicate that the dominant defects in CuSbSe 2 are V Cu and Cu i , which are shallow acceptor and donor defects, respectively. V Cu has higher population than other defects including Cu i , so the synthesized samples are usually p-type, but the conductivity may be tuned to intrinsic or even weakly n-type under Se poor condition.…”

Synthesis and characterization of copper antimony tin sulphide thin films for solar cell applications

“…4 (c) The S 2p core level and corresponding de-convoluted spectra (Fig. 4 (d) [24][25][26][27][28][29][30]. Therefore, combining the results of the binding energy values from the XPS and the phases from the XRD we assign the studied phase to be CuSbSnS 3 .…”