Recent research shows that the interface state in perovskite solar cells is the main factor which affects the stability and performance of the device, and interface engineering including strain engineering is an effective method to solve this issue. In this work, a CsBr buffer layer is inserted between NiOx hole transport layer and perovskite layer to relieve the lattice mismatch induced interface stress and induce more ordered crystal growth. The experimental and theoretical results show that the addition of the CsBr buffer layer optimizes the interface between the perovskite absorber layer and the NiOx hole transport layer, reduces interface defects and traps, and enhances the hole extraction/transfer. The experimental results show that the power conversion efficiency of optimal device reaches up to 19.7% which is significantly higher than the efficiency of the device without the CsBr buffer layer. Meanwhile, the device stability is also improved. This work provides a deep understanding of the NiOx/perovskite interface and provides a new strategy for interface optimization.
2D/3D perovskite heterostructures or composites are recognized as efficient strategies to improve the stability of perovskite solar cells. Herein, a novel solution process to develop 2D/3D perovskites with modulated diffusion passivation by introducing phenylethylammonium iodide (PEAI) and N,N‐dimethylformamide (DMF) additive, which could effectively enhance device performance and long‐term stability, is demonstrated. Compared with conventional devices, the device with PEAI and DMF solvent additive treatment exhibit enhanced charge transport, improved charge extraction, and suppressed nonradiative carrier recombination. The solar cells with an optimal 2D/3D perovskite passivation treatment exhibit an extremely high fill factor of 83.6% and an average power conversion efficiency of 21.4% (21.3% using integrated photocurrent from the incident photon‐to‐current efficiency spectra) based on the NiOx hole transport layer. Furthermore, the unencapsulated device exhibits excellent stability under continuously simulated sunlight illumination and outstanding air stability after 1000 h of storage under ambient air conditions.
Perovskite solar cells (PSCs) have been developed rapidly in recent years due to the excellent photoelectric properties and development potential. In this study, high performance and hysteresis-less planar structured perovskite (MA 1−y FA y PbI 3−x Cl x ) solar cell was successfully achieved via contact passivation of the compact titanium dioxide (TiO 2 )/ perovskite interface with NaCl doping method. It was found that the sodium chloride (NaCl) doping treatment on TiO 2 could significantly improve the electrical property of TiO 2 electron transport layer (ETL), and passivate the trap states at TiO 2 / perovskite interface. Moreover, the improved interface contact between TiO 2 ETL and perovskite could efficiently enhance the charge transfer and suppress the charge recombination in the device. Hence, the power conversion efficiency (PCE) of PSC device based on NaCl-doped TiO 2 was enhanced to 18.3% compared with the pristine compact TiO 2 -based PSCs (15.1%).
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