Pengfei Ouyang,Weiwei Li,Dingshan Zheng,Nian Cheng,Han Pan
All-inorganic CsPbBr3 perovskite solar cells exhibit excellent humidity and thermal stability compared with organic-inorganic hybrid perovskite solar cells. However, the proposed two-step spin-coating method for fabricating CsPbBr3 film using highly concentrated CsBr/H2O solution in the second step is prone to result in CsPbBr3 film with high defect density, which greatly limits the performance of CsPbBr3 perovskite solar cells. In this study, appropriate amount of NH4Ac is used as additive in the CsBr/H2O solution. The interaction of NH4Ac with CsPbBr3 could contribute to smooth and densified CsPbBr3 perovskite films with suppressed defect density. When carbon electrode based CsPbBr3 perovskite solar cells are fabricated, an optimized photovoltaic conversion efficiency of 8.77% is achieved using 0.50 mg mL-1 NH4Ac in CsBr/H2O solution, which is 23.35% higher than that of the reference perovskite solar cell (champion PCE = 7.11%). Furthermore, the optimized CsPbBr3 perovskite solar cell exhibits better long-term stability, which can maintain more than 85% of its initial efficiency after being placed for 30 days at an ambient temperature of 25 °C and a relative humidity of 30%~40%.
Kailin Chi,Yuechen Zhai,Yao Wang,Xin Zhang,Fucheng Liang,Shibo Wang
The achievement of complete conversion of PbBr 2 films presents a significant challenge in the development of CsPbBr 3 films with consistent growth, comprehensive coverage, and controllable components. To address this challenge, introducing a porous structure in the planar PbBr 2 film is advantageous for facilitating the immersion of CsBr precursor, thereby reducing impurity phase formation and mitigating strain caused by the film volume expansion. In order to accomplish this, indium tribromide (InBr 3 ) was employed as an additive and the InBr 3 (DMF) 3 adduct was utilized to expedite the release of organic molecules in PbBr 2 (DMF), resulting in the transformation of planar PbBr 2 film into porous structures. The growth orientation of PbBr 2 crystals was altered by this transformation, effectively suppressing the generation of metallic Pb impurities in the film. Additionally, it not only optimizes the morphology of CsPbBr 3 film but also reduces impurity phase. As a result, the InBr 3 :CsPbBr 3 perovskite solar cell achieved an efficiency of 7.28 %. The majority of In 3+ ions were concentrated near the buried interface between SnO 2 and InBr 3 :CsPbBr 3 , leading to significant improvements in both non-radiative recombination defect states within the perovskite film and electron injection and collection capabilities within the device.
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