Ruddlesden–Popper 2D Component to Stabilize γ‐CsPbI3 Perovskite Phase for Stable and Efficient Photovoltaics |
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Authors: | Kang Wang Zhizai Li Faguang Zhou Haoran Wang Hui Bian Hong Zhang Qian Wang Zhiwen Jin Liming Ding Shengzhong Liu |
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Affiliation: | Kang Wang,Zhizai Li,Faguang Zhou,Haoran Wang,Hui Bian,Hong Zhang,Qian Wang,Zhiwen Jin,Liming Ding,Shengzhong (Frank) Liu |
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Abstract: | The highest certified power conversion efficiency (PCE) of black phase based CsPbI3 perovskite solar cells has exceeded 18%, and become a hotspot in recent progress. However, the black phase of CsPbI3 rapidly transforms to yellow phase in ambient conditions due to its thermodynamic instability. Here, a Ruddlesden–Popper 2D structure is introduced into γ‐CsPbI3 film to stabilize the black phase via reducing dimensionality. It is found that a judicious amount of phenylethylammonium iodide can adjust the dimensionality of γ‐CsPbI3 film from 2D to quasi‐2D and 3D phase. Comprehensive consideration to obtain both the stability and high PCE, quasi‐2D (n = 40) γ‐CsPbI3 delivers a reproducible PCE of 13.65% with negligible hysteresis. By utilizing femtosecond transient absorption and time‐resolved PL decay, similar carrier kinetics in n = 40 and ∞ samples are observed, meaning an efficient charge extraction. More importantly, when the device is placed at 80 °C in N2 condition or in air with RH of 25–30%, its PCE keeps ≈88% and ≈89% of its initial PCE after 12 days, respectively. Such results are better than the 3D one (≈69% and ≈16%, respectively). |
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Keywords: | 2D efficiency Ruddlesden– Popper solar cells stability γ ‐CsPbI3 |
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