Degradation of perovskite solar cells (PSCs) is often found to be partially or fully reversible when the cells are allowed to recover in the dark. Unlike the dynamics of degradation, knowledge about the dynamics of PSC cell recovery is very limited. Here, we demonstrate that the PSC recovery strongly depends on the electrical bias conditions during the light-induced degradation and that it can be manipulated by applying an external electrical bias during the recovery phase. Investigation of the recovery dynamics allows us to analyze the degradation mechanisms in detail. More specifically, we aged a mixed-cation mixed-halide PSC with a n-i-p structure under illumination in open-circuit (OC) or short-circuit (SC) conditions, and periodically measured their characteristics during the recovery. PSCs aged in SC degrade faster and fully recover after the light is switched off, while the performance of the cells aged in OC does not recover but instead further decreases after the light is switched off (“drop-in-dark” effect). With the use of transient photoluminescence, secondary ion mass spectrometry, and drift-diffusion-based simulations, we hypothesize that extrinsic ion migration causes the drop-in-dark effect, by forming an electron extraction barrier at the metal oxide electron transport layer. The applied bias alleviates this effect. Our results are relevant for gaining a deeper understanding of the multiple degradation mechanisms present in perovskite solar cells, and for finding a practical way to assist their recovery.
Bibliografisk noteFunding Information:
M.M. acknowledges ‘Danmarks Frie Forskningsfond, DFF FTP for the funding of the project React-PV, no. 8022-00389B. V.T. and M.M. thank “Villum Foundation” for the funding of the project CompliantPV, under project number 13365. This work was supported by a research grant (17677) from VILLUM FONDEN. M.V.K. and E.A.K. acknowledge the support from the SNaPSHoTs project in the framework of the German-Israeli bilateral R&D cooperation in the feld of applied nanotechnology funded by the German Federal Ministry for Education and Research (BMBF) and the National Technological Innovation Authority of the State of Israel. Y.G. acknowledges the Ministry of Science and Technology of Taiwan (MOST) for funding the project with the number 110-2222-E-002-001-MY3. D.G. and I.D. acknowledge the support of Solliance, a partnership of R&D organizations from the Netherlands, Belgium, and Germany working in thin-film photovoltaic solar energy. All the authors acknowledge support via the COST action StableNextSol, MP1307. The numerical part has been supported by National Science Center, Poland 2018/29/N/ST7/02326. Calculations were carried out at the Academic Computer Center (CI TASK) in Gdansk.
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