Dual-layer synergetic optimization of high-efficiency planar perovskite solar cells using nitrogen-rich nitrogen carbide as an additive

Defects and energy-level offsets in distinct functional layers of perovskite solar cells (pero-SCs) are recognized obstacles to achieving their high efficiency and long-term stability. Herein, we report the meticulous design and positioning of nitrogen-rich nitrogen carbide (g-C3N5) as a multifunctional additive to simultaneously optimize the intrinsic defects of a SnO2 electron transport layer (ETL) and perovskite layer for high-performance pero-SCs. The synergistic effect of the favorable band alignment and improved electrical conductivity, obtained by precisely positioning g-C3N5, enables the power conversion efficiency (PCE) of pero-SCs to be increased from 18.05% (g-C3N5-free) to 20.68% and significantly enhances the photo/thermal stability. Moreover, this multiple optimization strategy is also generalized to CsFAMA-based pero-SCs, achieving a champion PCE of 22.34%. Theoretical and experimental analyses further reveal that the incorporating of g-C3N5 regulates the crystalline quality, passivates grain boundary/surface defects and boosts the moisture resistance of photovoltaic devices. This work proves the charming properties and ingenious design of g-C3N5 as a multifunctional material for a variety of optoelectronic devices, including light-emitting diodes, photodetectors, sensors, etc.

Automated summary

This study demonstrates that the addition of nitrogen-rich nitrogen carbide (g-C3N5) can optimize the defects in the SnO2 electron transport layer and perovskite layer of perovskite solar cells, leading to improved efficiency and stability. This optimization strategy is applicable to different types of perovskite solar cells and shows promising performance.