Buried interface engineering with amphoteric ion for inverted perovskite solar cells

Abstract

The efficiency of perovskite solar cells (PSCs) primarily depends on the quality of the perovskite films. The buried interface, located at the bottom surface of the perovskite layer, significantly influences the performance of perovskite photovoltaics. This study utilizes cetyltrimethylammonium bromide (CTAB), an amphoteric organic salt, on the surface of poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT: PSS) to modify the bottom interface between the perovskite film and the hole transport layer. The ammonium group and bromine ion in CTAB can passivate vacancy defects at the PEDOT: PSS/perovskite interface, while the long carbon chain enhances the humidity stability of PEDOT: PSS. The application of CTAB significantly improved the photoelectric performance of PSCs, increasing the power conversion efficiency (PCE) from 15.16 to 17.30%, with excellent reproducibility. The unencapsulated device retained over 60% of its initial PCE after 400 h. As an emerging technology, modifying the buried interface of the perovskite film presents new strategies for achieving high-performance and long-lasting PSCs.