Efficient and stable inverted structure organic solar cells utilizing surface-modified SnO2 as the electron transport layer

Organic solar cells (OSCs) with an inverted structure have the potential to exhibit both high efficiency and stability, in which the electron transport layer (ETL) plays a crucial role. In this study, we have developed an efficient ETL for inverted structure OSCs by modifying commercially available SnO2 nanoparticles with a simple molecule 2-(3-(dimethylamino)propyl)− 1,3-dioxo-2,3-dihydro-1 H-benzo[de]isoquinoline-6,7-dicarboxylic acid (NMA). The surface modification effectively eliminates the light soaking issue observed in devices with bare SnO2. Furthermore, it significantly enhances the efficiency and stability of the photovoltaic devices. With the hybrid ETL, the device based on PM6:L8-BO achieves an outstanding power conversion efficiency (PCE) of 18.33 %. Notably, the champion device exhibits excellent shelf, thermal and photo stabilities. It maintained 99.7 % and 87.1 % of its original efficiency under storage in N2 and thermal stress at 65 ℃ for 1000 h, respectively. Under continuous 1-sun illumination with maximum power point tracking for 800 h, the device retained 86.6 % of its initial efficiency. Additionally, the hybrid ETL shows good generality on other typical active layer systems based-OSCs. This work presents an effective hybrid ETL approach for the development of high-performance OSCs.