Interface Engineering via Sputtered Oxygenated CdS:O Window Layer for Highly Efficient Sb₂Se₃ Thin‐Film Solar Cells with Efficiency Above 7%

Abstract

Antimony chalcogenide Sb2Se3 is an emerging photovoltaic absorber due to its appropriate bandgap (≈1.1 eV), high absorption coefficient (>105 cm−1), suitable p‐type conductivity, low toxicity, earth abundance, and excellent stability. However, the stringent growth condition and low photovoltage limit its power conversion efficiency (PCE). Herein, via a combined theoretical and experimental study, interface engineering via an oxygenated cadmium sulfide (CdS) window layer (CdS:O) is found to be an effective approach to improve the device performance of CdS:O/Sb2Se3 solar cells. The sputtered oxygenated CdS:O window layer can be used to replace conventional chemical‐bath‐deposited CdS window layer in the Sb2Se3 devices. The best PCE of 7.01% is demonstrated in the superstrate configuration of fluorine‐doped SnO2/CdS:O/Sb2Se3/graphite with a high open‐circuit voltage of 0.432 V, where Sb2Se3 is fabricated using the close space sublimation technique. The interfacial diffusion between Sb2Se3 and sputtered CdS:O is significantly suppressed by introducing oxygen at the interface, which prevents Cd diffusion and the formation of Cd interstitials. Combined device physics characterizations and theoretical calculations reveal that oxygen in the CdS:O/Sb2Se3 interface can increase depletion region, built‐in voltage, and reduce interfacial recombination. These findings provide the guidance to optimize quasi‐one‐dimensional non‐cubic earth‐abundant chalcogenide photovoltaic devices through interface engineering.

Intrinsic Defect Limit to the Electrical Conductivity and a Two‐Step p‐Type Doping Strategy for Overcoming the Efficiency Bottleneck of Sb2S3‐Based Solar Cells

“…Furthermore, Guo et al found interestingly that the oxygenated CdS:O window layer can efficiently improve the efficiency of Sb 2 Se 3 solar cell, and the oxygen is accumulated at the interface between CdS:O and Sb 2 Se 3 layers . Their calculations showed that O Se has very low formation energy, similar to O S in Sb 2 S 3 (Figure ).…”

High‐Efficiency Sb2(S,Se)3 Solar Cells with New Hole Transport Layer‐Free Back Architecture via 2D Titanium‐Carbide Mxene

“…We can find that the MXene‐derived device in our work is the first time to join the club of over 8% efficiency using the noble metal and/or organic‐free BCMs for Sb 2 (S x Se 1− x ) 3 solar cells. [ 10–13,15,56–64 ] This back contact engineering strategy, via the novel, stable, and eco‐friendly BCMs of MXene electrode, enables to achieve a low‐cost and full‐inorganic Sb 2 (S,Se) 3 solar cell with high efficiency.…”

Boosting VOC of antimony chalcogenide solar cells: A review on interfaces and defects

“…A similar approach was introduced by applying a CdS:O ETL for Sb 2 Se 3 solar cells, and the CdS:O layer was deposited by a sputtering method. [74] The sputtered oxygenated CdS ETL to the interstitial sites in the vdW gap, which facilitated the formation of Sb-O-Se chain. [75]…”

“…A similar approach was introduced by applying a CdS:O ETL for Sb 2 Se 3 solar cells, and the CdS:O layer was deposited by a sputtering method. [ 74 ] The sputtered oxygenated CdS:O ETL provided a well‐matched band alignment with the Sb 2 Se 3 absorber, leading to a higher V OC . More importantly, the oxygen in CdS:O can not only effectively passivate the vdW gap of Sb 2 Se 3 but also tailor the (Sb 4 Se 6 ) n ribbons to (221)‐textured orientation.…”