Modeling of Ag incorporated Sb[formula omitted](S[formula omitted]Se[formula omitted])[formula omitted] bi-layer devices: Enhanced bi-layer absorber configuration

Abstract

In this contribution, we proposed Ag incorporated Sb2(SxSe1−x)3 bi-layer solar cells by modeling and simulation to optimize the absorber layer. Firstly, as the sulfur composition increases, we have investigated simple single-layer devices with the absorber film of each AgSb(SxSe1−x)3 and Sb2(SxSe1−x)3 as a frame of reference. Secondly, the impact of sulfur composition on bi-layer devices has been studied with two different absorber configurations such as Sb2(SxSe1−x)3/AgSb(SxSe1−x)3 and AgSb(SxSe1−x)3/Sb2(SxSe1−x)3. Compared with any single-layer devices, the absorber configuration of AgSb(S0.4Se0.6)3/Sb2(S0.4Se0.6)3 bi-layers shows best performance at the sulfur composition, x = 0.4. This is caused by the reduced effective Schottky barrier (by 126 mV) at the back contact, improving the roll-over effect by 4.3 times at 1 V. The resulting efficiency is 18.6 %, Voc (778.9 mV), Jsc (37.2 mA/cm2), and FF (64.0 %). Once the devices with highest efficiency and the optimal sulfur composition are identified, a set of different device parameters have been studied to optimize these bi-layer devices further. With AgSb(S0.4Se0.6)3/Sb2(S0.4Se0.6)3 bi-layer devices, the result from various doping concentration of each bi-layers indicates that doping concentration of AgSb(S0.4Se0.6)3 is responsible for Jsc, while the doping concentration of Sb2(S0.4Se0.6)3 dictates Voc under certain doping concentration of AgSb(S0.4Se0.6)3 (approximately 1 × 1015/cm2). The best efficiency is 21.4% with Voc (822 mV), Jsc (38.1 mA/cm2), and FF (68.4%).