Double-side improved charge extraction via 2D perovskite for efficient inverted perovskite solar cells

Modulating perovskite heterointerface is critical to enhance charge extraction and improve photovoltaic performance of perovskite solar cells (PSCs). Herein, 2D perovskite is integrated at double sides of 3D perovskite to concurrently enhance charge extraction at both hole- and electron-selective interfaces, enabling high-performance inverted p-i-n PSCs. Notably, the bottom 2D perovskite forms cascade energetics at 3D perovskite layer and hole transport layer interface for largely diminishing thermionic losses for hole extraction, passivates defects at the bottom heterointerface, and enhances epitaxial crystallization of the upper 3D perovskite film. It is revealed that the top 2D perovskite that improves energetic alignment between 3D perovskite layer and electron transport layer, effectively promotes electron extraction at the top heterointerface. With double-side 2D perovskite modification, the nonradiative recombination losses are significantly suppressed simultaneously at hole- and electron-selective contacts in one device. Consequently, the inverted PSCs with such 2D/3D/2D modification achieve a champion efficiency 25.25 % with excellent stability, which remarkably surpasses the efficiency 24.58 % of the devices with the widely used 3D/2D heterojunction at the top heterointerface.