Gradient layer arrangement for modulating the buried interface of inverted perovskite solar cells

This paper reports the multifunctional surface modulation of 3MTPAI , an ionic compound , to improve the photovoltaic performance of PSCs . Theoretical calculation and experimental characterization show that 3MTPAI increases the dipole moment of SAM layer. this makes the arrangement of SAM layers more orderly, which may be beneficial to the crystallization quality of PVK . 3MTPAI also passivates the undercoordinated Pb defect and halide vacancy at the interface, improves the lattice strain, and optimizes the energy level matching between SAM and PVK. The interfacial energy level arrangement promotes carrier transport and effectively passivates the defects. The results showed that the PCE of PSCs with 3MTPAI was 25.30%. • 3MTPAI can increase the dipole moment of SAM layer, guide the arrangement of hole layer and improve the quality of PVK. • 3MTPAI can passivate Pb defects and halide vacancies. • 3MTPAI can improves lattice strain and promotes charge carrier transport. • 3MTPAI enhances the stability of perovskite under thermal and ambient conditions. • The devices with 3MTPAI realize an enhanced PCE of 25.30 %. The surface modification of transparent conductive oxides with self-assembled monolayers (SAM) based on carbazole has been demonstrated to be a workable strategy for the formation of efficient hole-selective contacts, thus significantly enhancing the power conversion efficiency (PCE) and stability of p-i-n perovskite solar cells (PSCs). While the inherent monolayer nature of SAM offers unique advantages, the buried interface poses a significant challenge to synergistic regulation for both perovskite (PVK) and SAM. In this study, an interfacial layer composed of an ionic compound, 3-(methylthio) propylamine hydroiodide (3MTPAI), is introduced between the PVK and SAM layers to enhance the photovoltaic performance of PSCs . 3MTPAI has been demonstrated to enhance the ion–dipole interactions of the SAM, facilitating a better-matched energy level between the PVK and hole transport layer (HTL). This, in turn, improves hole extraction/transport from the PVK layer to the HTL and reduces carrier recombination of the PSCs . Consequently, the PCE of the PSCs modified with 3MTPAI increases from 23.90 % to 25.30 %. Furthermore, devices treated with 3MTPAI exhibit enhanced stability, maintaining 90 % of the original PCE after 1000 h under conditions of 55 ± 5 % RH. Therefore, the buried interface modification strategy employing dual-role 3MTPAI molecules emerges as a viable approach to enhance the efficiency and stability of PSCs .