Indium-less and indium-free inverted perovskite solar cells using sputtered tin oxide transparent electrodes

Abstract

Indium-based transparent electrodes are widely used in perovskite solar cells (PSCs). However, the limited supply and high cost of rare indium may become an obstacle in the rapid development of PSCs. In this work, indium-less or indium-free inverted PSCs were prepared using sputtered antimony-doped tin oxide (ATO) films instead of indium tin oxide (ITO) films as front transparent electrodes. ATO films exhibited a carrier concentration, mobility, and average visible light transmittance of 1.88 × 10²⁰ cm⁻³, 3.38 cm²/V·s, and 82.64 %, respectively. The inverted PSCs using 165 nm ITO, 140 nm ATO/25 nm ITO, and 280 nm ATO transparent electrodes exhibited power conversion efficiency (PCE) of 20.96 %, 19.73 %, and 17.20 %, respectively. In other words, the decrease in PCE was 5.9 % and 17.9 % for indium-less and indium-free PSCs, respectively, compared with the reference indium-based PSC. Further improving the electrical conductivity of ATO films can mitigate the PCE decline. Furthermore, both the thermal and humidity stability of PSCs with ITO, ATO/ITO, and ATO transparent electrodes improved in sequence. After heating at 85℃ for 400 h, the devices with ITO, ATO/ITO, and ATO electrodes retained 57.6 %, 63.3 %, and 65.7 % of their initial efficiency, respectively. After exposure to 30 ± 10 RH% for 800 h, PSCs with ITO, ATO/ITO, and ATO electrodes retained 46.6 %, 56.0 %, and 60.5 % of their initial efficiency, respectively. The improved stability was mainly attributed to less increase in both device defect density and electrode sheet resistance. The first demonstration of indium-less or indium-free inverted PSCs provides a strategy for the sustainable development of PSCs industry.