Preparing high-quality perovskite film with large grain size and fewer trap states is of vital importance in boosting the efficiency and stability of perovskite solar cells (PSCs). However, it is still difficult to obtain perfect MAPbI 3 films by antisolvent treatment so far because of the small grain size, pinholes, and numerous defects in perovskite layers. Herein, acetonitrile (ACN) was introduced into chlorobenzene (CB) antisolvent to modify the MAPbI 3 active layer. The results show that the ACN could control the ratio of the DMSO in MAI−PbI 2 −DMSO intermediate phase film effectively and thus manipulate the formation of MAPbI 3 film. Relatively high-quality perovskite films with larger grain size were obtained when we added 6% v/v ACN into CB antisolvent. Based on the ACN-modified MAPbI 3 film, the n-i-p planar device with the structure of FTO/SnO 2 /MAPbI 3 / spiro-OMeTAD/Ag yields the best power conversion efficiency (PCE) of 18.9%. It exhibited an enhancement of 16.6% in efficiency compared with the PCE of 16.2% for the control device. In addition, the device based on ACN-modified MAPbI 3 also presents improved stability in air atmosphere.
As one of the more promising potential photovoltaic technologies, planar perovskite solar cells (PSCs) are arousing worldwide interest for their many advantages. Now, PSCs are being developed toward the direction of highperformance and longevity. However, the defects of the polycrystalline perovskite active layer limit further improvement of the device performance. Seeking simple and efficient strategies to reduce these trap states in the perovskite active layer is highly desirable. Here, a novel nonfunctionalized fullerene C 60 o-quinodimethane bisadduct [C 60 (QM) 2 ] was dissolved in chlorobenzene (CB) solvent and introduced into a CH 3 NH 3 PbI 3 active layer by antisolvent dripping. Results showed that the introduced C 60 (QM) 2 could effectively reduce the trap density of the MAPbI 3 active layer, facilitating carrier extraction/ injection from CH 3 NH 3 PbI 3 to spiro-OMeTAD. As a result, a highest PCE of 18.4% for the PSC based on CH 3 NH 3 PbI 3 / C 60 (QM) 2 was obtained, which increased by 10.1% compared with 16.7% for the reference device. Meanwhile, the air stability for C 60 (QM) 2 -passivated PSCs was also improved significantly. This approach provides a direction for designing highly efficient and air stable PSCs.
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