Enhancing the photovoltaic performance of planar heterojunction perovskite solar cells via introducing binary-mixed organic electron transport layers

Optimizing electron transport layers (ETLs) is a significant way to enhance the photovoltaic performance and stability of inverted perovskite solar cells (PSCs). Herein, we introduce a strategy focused on binary-mixed organic ETLs, which dopes an n-type small organic molecule, m-ITTC, into the fullerene [6,6]-phenyl C-61-butyric acid methyl ester (PCBM) ETLs to fabricate a binary-mixed organic ETLs for use in inverted PSCs. The binary-mixed organic ETLs have suitable energy level alignment at the interface between the perovskite and ETLs, and thus the charge recombination behavior is modified. The PSCs modified with the binary-mixed organic ETLs exhibit a power conversion efficiency (PCE) of 15.62% with negligible hysteresis. Additionally, the binary-mixed organic ETLs can not only effectively prevent moisture intrusion, but also alleviate aggregation under continuous operation, so as, compared to PCBM ETLs, the devices with the binary-mixed organic ETLs exhibit better stability with a T95 of the best-performing devices exceeding 200 h. This work represents a simple and effective way to enhance the efficiency and stability of PSCs.