Efficiency Potential and Voltage Loss of Inorganic CsPbI2Br Perovskite Solar Cells. Issue 11 (20th September 2022)

• Record Type: Journal Article
• Authors: Grischek, Max; Caprioglio, Pietro; Zhang, Jiahuan; Peña-Camargo, Francisco; Sveinbjörnsson, Kári; Zu, Fengshuo; Menzel, Dorothee; Warby, Jonathan H.; Li, Jinzhao; Koch, Norbert; Unger, Eva; Korte, Lars; Neher, Dieter; Stolterfoht, Martin; Albrecht, Steve
• Is Part Of: Solar RRL. Volume 6:Issue 11(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-09-20
• Subjects: CsPbI2Br -- efficiency potentials -- inorganic perovskites -- photoluminescence -- solar cells -- voltage losses; Solar energy -- Periodicals; Photovoltaic power generation -- Periodicals; Solar energy -- Research -- Periodicals; Photovoltaic power generation -- Research -- Periodicals; Periodicals; 333.7923
• DOI: 10.1002/solr.202200690
• Languages: English
• ISSNs: 2367-198X

Abstract

Abstract : Inorganic perovskite solar cells show excellent thermal stability, but the reported power conversion efficiencies are still lower than for organic–inorganic perovskites. This is mainly caused by lower open‐circuit voltages ( V OC s). Herein, the reasons for the low V OC in inorganic CsPbI2 Br perovskite solar cells are investigated. Intensity‐dependent photoluminescence measurements for different layer stacks reveal that n–i–p and p–i–n CsPbI2 Br solar cells exhibit a strong mismatch between quasi‐Fermi level splitting (QFLS) and V OC . Specifically, the CsPbI2 Br p–i–n perovskite solar cell has a QFLS– e · V OC mismatch of 179 meV, compared with 11 meV for a reference cell with an organic–inorganic perovskite of similar bandgap. On the other hand, this study shows that the CsPbI2 Br films with a bandgap of 1.9 eV have a very low defect density, resulting in an efficiency potential of 20.3% with a MeO–2PACz hole‐transporting layer and 20.8% on compact TiO2 . Using ultraviolet photoelectron spectroscopy measurements, energy level misalignment is identified as a possible reason for the QFLS– e · V OC mismatch and strategies for overcoming this V OC limitation are discussed. This work highlights the need to control the interfacial energetics in inorganic perovskite solar cells, but also gives promise for high efficiencies once this issue is resolved. Abstract : The efficiency potential of inorganic n–i–p and p–i–n CsPbI2 Br solar cells is quantified using intensity‐dependent photoluminescence measurements. A detailed loss analysis reveals the contribution of each charge transport layer to the voltage and fill factor losses. This study provides insights into the loss mechanisms and presents strategies for improvement.