Abstract
Understanding the kinetic competition between charge extraction and recombination, and how this is impacted by mobile ions, remains a key challenge in perovskite solar cells (PSCs). Here, this issue is addressed by combining operando photoluminescence (PL) measurements, which allow the measurement of real-time PL spectra during current–voltage (J–V) scans under 1-sun equivalent illumination, with the results of drift-diffusion simulations. This operando PL analysis allows direct comparison between the internal performance (recombination currents and quasi-Fermi-level-splitting (QFLS)) and the external performance (J–V) of a PSC during operation. Analyses of four PSCs with different electron transport materials (ETMs) quantify how a deeper ETM LUMO induces greater interfacial recombination, while a shallower LUMO impedes charge extraction. Furthermore, it is found that a low ETM mobility leads to charge accumulation in the perovskite under short-circuit conditions. However, thisalone cannot explain the remarkably high short-circuit QFLS of over 1 eV which is observed in all devices. Instead, drift-diffusion simulations allow this effect to be assigned to the presence of mobile ions which screen the internal electric field at short-circuit and lead to a reduction in the short-circuit current density by over 2 mA cm−2 in the best device.
Original language | English (US) |
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Article number | 2301102 |
Journal | Advanced Energy Materials |
Volume | 13 |
Issue number | 36 |
DOIs | |
State | Published - Sep 22 2023 |
Bibliographical note
Publisher Copyright:© 2023 The Authors. Advanced Energy Materials published by Wiley-VCH GmbH.
Keywords
- charge accumulation
- charge extraction
- drift-diffusion simulation
- ion migration
- operando photoluminescence spectroscopy
- perovskite solar cells
- quasi-Fermi level splitting
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- General Materials Science