Enhanced electron transfer dynamics in perylene diimide passivated efficient and stable perovskite solar cells

Abstract

AbstractInterfacial engineering for passivating perovskite surface defects and reducing nonradiative recombination loss has been proven to be an effective strategy to fabricate highly efficient and stable perovskite solar cells (PSCs). However, the detailed understanding of the original role of interface materials on the charge‐carriers transfer dynamics of electron transport layer (ETL) remains lacking. Herein, a perylene diimide (PDI) was engineered onto perovskite surfaces to afford passivation of undercoordinated surface defects, which correlates this with the improvement of photovoltaic performance and stability of PSCs. Extensively experimental and theoretical studies reveal that PDI molecule can effectively modulate the surface properties of perovskite film through not only interaction of carbonyl groups in PDI with surface defects but also formation of close‐packed superstructure of PDI onto perovskite surfaces. Consequently, the PDI‐treated PSCs exhibits an increase of power conversion efficiency from 19.52% to 22.24% with an excellent stable device maintaining 95% of its initial value for 900 h in ~45% relative humidity. Importantly, transient absorption spectroscopic measurements further provide an evidence for the origin of the improved photovoltaic performance in PDI‐treated PSCs device, in which the modulation of PDI enhanced the electron transfer across ETL interface more efficiently. Our study provides new insights to understand the effect of interfacial material on the charge‐carrier transfer dynamics in PSCs device.image