Effects of 4-tert-butylpyridine on perovskite formation and performance of solution-processed perovskite solar cells

Abstract

To obtain highly efficient perovskite solar cells (PSCs), effective controls on perovskite crystallinity, homogeneity, and surface morphology are crucial. Herein, we demonstrate the flexible and facile use of TBP to improve the crystallinity of perovskite in two-step or one-step routes. For the two-step route, addition of TBP into DMF when dissolving PbI₂ for spin-coating resulted in a porous layer composed of randomly packed PbI₂ nanocrystals. This approach subsequently offered a widely enlarged contact area facilitating interfacial reaction with CH₃NH₃I and greatly improved CH₃NH₃PbI₃ crystallization. Based on this strategy, PCEs of CH₃NH₃PbI₃-based PSCs were improved from 6.71% to 10.62% (i.e., 58% enhancement). For the one-step route, TBP as an additive resulted in orientational and better crystallinity, by which the PCEs of CH₃NH₃PbI_3−xCl_x-based planar PSCs increased from 11.11% to 15.01%, showing a remarkable enhancement as high as 35%. Using TBP as one multifunctional additive, it is thought that our strategy in this work offers a new idea for the fabrication of highly efficient PSCs.