Over 7% Efficiency of Sb₂(S,Se)₃ Solar Cells via V‐Shaped Bandgap Engineering

Abstract

Antimony chalcogenides (including Sb2S3, Sb2Se3, and Sb2(S,Se)3 alloy) have emerged as promising solar absorber materials. Notably, the Sb2(S,Se)3 alloy possesses continuously tunable bandgap from 1.1 to 1.7 eV, which covers the ideal bandgap for single‐junction photovoltaics governed by the Shockley–Queisser theory. Moreover, the bandgap gradient provides effective ways for photogenerated carriers collection and has the potential for high‐efficient Sb2(S,Se)3 alloy solar cells. Herein, a V‐shaped distributional bandgap in Sb2(S,Se)3 solar cells is reported through a simple dual‐source vapor transport deposition process, enabling the synergetic increase of the open‐circuit voltage (VOC) and short‐circuit current (JSC). Through careful optimization, a power conversion efficiency of 7.27% under AM1.5G illumination is obtained, with VOC and JSC of 0.46 V and 29.6 mA cm−2, respectively. This V‐shaped bandgap engineering provides an effective method to enhance the device performance and can be extended to other chalcogenide thin‐film solar cells such as Sn–X, Ge–X, Cu–Sb–X (X = S and Se), and so on.

Vapor Transport Deposition of Highly Efficient Sb2(S,Se)3 Solar Cells via Controllable Orientation Growth

“…[ 1–5 ] With advantages of high natural abundance, high optical absorption coefficient (≈10 5 cm −1 ), and non‐toxicity of the constituent elements, [ 6–8 ] antimony chalcogenide solar cells are viewed as highly potential alternatives to the traditional thin film production technologies such as CdTe and Cu(In,Ga)Se 2 solar cells. [ 9,10 ] An attractive feature of this material is its ability to tune its bandgap from about 1.1 to 1.7 eV by adjusting the S/(S+Se) ratio, [ 11,12 ] indicating that it well matches the desired bandgap according to the Shockley–Queisser limit; [ 13 ] therefore, the cell performance can be improved. Furthermore, it possesses a high‐saturated vapor pressure that offers a promising route for a cost‐efficient and industrially high‐throughput vapor transport deposition process (VTD) at a large scale, developed in the most commercially successful CdTe photovoltaics technologies.…”

“…[ 21 ] So far, Sb 2 Se 3 and Sb 2 (S,Se) 3 solar cells based on superstrate configuration attained outstanding PCEs of 7.6% and 7.27% by VTD. [ 11,15 ] However, the VTD process, the first to achieve an efficient threshold in this field, has not progressed for quite some time already, which is seriously limited by the composition tuneability and orientation controllability of the large‐grained dense Sb 2 (S,Se) 3 absorber layer. [ 2,15,20,28 ]…”

Systematic Variation of Material Characteristics with Chemical Composition in Antimony Sulfide Selenide Thin Films and Its Relevance to Solar Cell Performance

“…[ 1,51 ] In antimony sulfide selenide solar cells, the change in the chemical composition along the thickness, even when it exists, can be well utilized in “bandgap engineering” to improve the V oc of the cells. [ 21 ]…”

“…[ 20 ] A “V‐type bandgap engineering” applied to modify the E g of the Sb 2 S x Se 3– x absorber along its thickness offered η of 7.27%. [ 21 ] Simulations of the performance of these cells with different contact materials and configurations reported during 2019–20 suggest that an efficiency of 20% may be achieved in them. [ 22,23 ] We describe here a step‐by‐step methodology for the development of solar cells and prototype PV modules of Sb 2 S x Se 3– x with different compositions (A – E) from a dual‐source thermal evaporation system.…”

Filter‐free self‐power CdSe/Sb2(S1−x,Sex)3 nearinfrared narrowband detection and imaging

“…Thus, CdSe can serve as the partner in the p–n junction NIR narrowband detector combining with a suitable p‐type material. Antimony‐sulfur‐selenium (Sb 2 (S 1−x ,Se x ) 3 ) is a p‐type semiconductor with high absorption coefficient 24–26 and a continuously adjustable absorption cutoff edge (from 730 to 1050 nm) 27 . In recent years, Sb 2 (S 1−x ,Se x ) 3 thin‐film solar cells have achieved an efficiency of >10% 28 and also attracted wide attention as NIR PDs 29 .…”