The impact of energy alignment and interfacial recombination on the internal and external open-circuit voltage of perovskite solar cells
| Autor: | Fengshuo Zu, José A. Márquez, Steve Albrecht, Joleik Nordmann, Martin Stolterfoht, Thomas Unold, Thomas Kirchartz, Christian M. Wolff, Lukas Kegelmann, Shanshan Zhang, Alex Redinger, Norbert Koch, Yohai Amir, Daniel Rothhardt, Dieter Neher, Pietro Caprioglio, Ulrich Hörmann, Michael Saliba |
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| Rok vydání: | 2019 |
| Předmět: |
Work (thermodynamics)
Photoluminescence Materials science Physics [G04] [Physical chemical mathematical & earth Sciences] 02 engineering and technology 010402 general chemistry 01 natural sciences Capacitance ddc:690 Environmental Chemistry ddc:530 Perovskite (structure) Range (particle radiation) Renewable Energy Sustainability and the Environment business.industry Open-circuit voltage Institut für Physik und Astronomie Heterojunction 021001 nanoscience & nanotechnology Pollution 0104 chemical sciences Physique [G04] [Physique chimie mathématiques & sciences de la terre] Nuclear Energy and Engineering Optoelectronics 0210 nano-technology business Ultraviolet photoelectron spectroscopy |
| Zdroj: | Energy & environmental science 12(9), 2778-2788 (2019). doi:10.1039/C9EE02020A |
| ISSN: | 1754-5706 1754-5692 |
| DOI: | 10.1039/c9ee02020a |
| Popis: | Charge transport layers (CTLs) are key components of diffusion controlled perovskite solar cells, however, they can induce additional non-radiative recombination pathways which limit the open circuit voltage (V-OC) of the cell. In order to realize the full thermodynamic potential of the perovskite absorber, both the electron and hole transport layer (ETL/HTL) need to be as selective as possible. By measuring the photoluminescence yield of perovskite/CTL heterojunctions, we quantify the non-radiative interfacial recombination currents in pin- and nip-type cells including high efficiency devices (21.4%). Our study comprises a wide range of commonly used CTLs, including various hole-transporting polymers, spiro-OMeTAD, metal oxides and fullerenes. We find that all studied CTLs limit the V-OC by inducing an additional non-radiative recombination current that is in most cases substantially larger than the loss in the neat perovskite and that the least-selective interface sets the upper limit for the V-OC of the device. Importantly, the V-OC equals the internal quasi-Fermi level splitting (QFLS) in the absorber layer only in high efficiency cells, while in poor performing devices, the V-OC is substantially lower than the QFLS. Using ultraviolet photoelectron spectroscopy and differential charging capacitance experiments we show that this is due to an energy level mis-alignment at the p-interface. The findings are corroborated by rigorous device simulations which outline important considerations to maximize the V-OC. This work highlights that the challenge to suppress non-radiative recombination losses in perovskite cells on their way to the radiative limit lies in proper energy level alignment and in suppression of defect recombination at the interfaces. |
| Databáze: | OpenAIRE |
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