Effects of Residual DMSO Adduct on Photonically Cured MAPbI3 Solar Cells

Defects and impurities in halide perovskite solar cells can negatively impact device performance and long-term stability. In this study, we identify photonically cured methylammonium (MA) lead iodide films containing a residual adduct, MA2Pb3I8(dimethyl sulfoxide)2 (MA2Pb3I8(DMSO)2), which reduces photocurrent generation in perovskite solar cells (PSCs). This is evidenced by a decrease in the external quantum efficiency (EQE) near 400 nm. Similar EQE reductions were observed in PSCs produced using high-speed processes but have not been thoroughly examined. Through X-ray diffraction patterns and Fourier transform infrared spectroscopy, we establish the photoinactive MA2Pb3I8(DMSO)2 as the culprit for the EQE reduction. Combined experimental and simulation results reveal that the MA2Pb3I8(DMSO)2 phase is located at the hole transport layer/interface, not on the surface, resulting in lower quantum efficiency and surface photovoltage in the short-wavelength region. The residual adduct is kinetically trapped due to the short processing time (20 ms) and crystallization direction but can be removed by an additional photonic pulse. This study highlights the need for careful examination of resulting materials beyond device efficiency when transitioning from laboratory processing to industrial high-speed methods.