A Universal Double‐Side Passivation for High Open‐Circuit Voltage in Perovskite Solar Cells: Role of Carbonyl Groups in Poly(methyl methacrylate). Issue 30 (14th September 2018)

• Record Type: Journal Article
• Authors: Peng, Jun; Khan, Jafar I.; Liu, Wenzhu; Ugur, Esma; Duong, The; Wu, Yiliang; Shen, Heping; Wang, Kai; Dang, Hoang; Aydin, Erkan; Yang, Xinbo; Wan, Yimao; Weber, Klaus J.; Catchpole, Kylie R.; Laquai, Frédéric; De Wolf, Stefaan; White, Thomas P.
• Is Part Of: Advanced energy materials. Volume 8:Issue 30(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-09-14
• Subjects: carbonyl group -- nonradiative recombination -- passivation -- perovskite solar cells -- undercoordinated Pb atoms; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.201801208
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: The performance of state‐of‐the‐art perovskite solar cells is currently limited by defect‐induced recombination at interfaces between the perovskite and the electron and hole transport layers. These defects, most likely undercoordinated Pb and halide ions, must either be removed or passivated if cell efficiencies are to approach their theoretical limit. In this work, a universal double‐side polymer passivation approach is introduced using ultrathin poly(methyl methacrylate) (PMMA) films. Very high‐efficiency (≈20.8%) perovskite cells with some of the highest open circuit voltages (1.22 V) reported for the same 1.6 eV bandgap are demonstrated. Photoluminescence imaging and transient spectroscopic measurements confirm a significant reduction in nonradiative recombination in the passivated cells, consistent with the voltage increase. Analysis of the molecular interactions between perovskite and PMMA reveals that the carbonyl (CO) groups on the PMMA are responsible for the excellent passivation via Lewis‐base electronic passivation of Pb 2+ ions. This work provides new insights and a compelling explanation of how PMMA passivation works, and suggests future directions for developing improved passivation layers. Abstract : Interface recombination is a dominant loss mechanism in perovskite solar cells. Double‐side passivation of perovskite solar cells using ultrathin films of poly(methyl methacrylate) (PMMA) can boost open circuit voltages up to 1.22 V. This results from the carbonyl (CO) group of the Lewis‐base polymer PMMA, which effectively passivates under‐coordinated Pb atoms (Pb 2+ ) at the perovskite/transport layer interfaces.