Embedding gold nanoparticles in the SnO₂ electron transport layer for boosting flexible perovskite solar cells with the efficiency over 23%

Flexible perovskite solar cells (f-PSCs) exhibit superior potential applications in space energy, mobile energy, portable energy due to the characteristics of cost-effective large-scale processing, high efficiency, and power-to-weight. It is significant to improve the electron extraction and transport in the electron transport layer (ETL) to enhance the power conversion efficiency (PCE) of f-PSCs. Herein, we report a highly efficient SnO₂ ETL embedded by gold nanoparticles (Au NPs) that obviously boost the PCE of f-PSCs. The high-conductivity Au NPs can improve the electrical properties of ETL by enhancing the conductivity and electron mobilities, which dramatically promote the electron extraction and transport, resulting in the decrease in charge recombination at the ETL/perovskite interface. An impressive PCE of 23.08% can be achieved for the f-PSCs with SnO₂ ETL embedded Au NPs, which is much higher than the reference f-PSCs with the PCE of 21.65% utilizing pristine SnO₂ ETL. This work presents an innovative approach for the fabrication of high-efficiency f-PSCs, which is compatible with the roll-to-roll manufacturing process.