Understanding and tailoring the physical behaviour of halide perovskites under practical environments is critical for designing efficient and durable optoelectronic devices. Here, we report that continuous light illumination leads to >1% contraction in the out-of-plane direction in two-dimensional hybrid perovskites, which is reversible and strongly dependent on the specific superlattice packing. X-ray photoelectron spectroscopy measurements show that constant light illumination results in the accumulation of positive charges in the terminal iodine atoms, thereby enhancing the bonding character of inter-slab I–I interactions across the organic barrier and activating out-of-plane contraction. Correlated charge transport, structural and photovoltaic measurements confirm that the onset of the light-induced contraction is synchronized to a threefold increase in carrier mobility and conductivity, which is consistent with an increase in the electronic band dispersion predicted by first-principles calculations. Flux-dependent space-charge-limited current measurement reveals that light-induced interlayer contraction activates interlayer charge transport. The enhanced charge transport boosts the photovoltaic efficiency of two-dimensional perovskite solar cells up to 18.3% by increasing the device’s fill factor and open-circuit voltage.
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The work at Rice University was supported by the US Department of Defense Short-Term Innovative Research (STIR) programme funded by the Army Research Office. J. Even acknowledges the financial support from the Institut Universitaire de France. W.L. acknowledges the National Science Foundation Graduate Research Fellowship Program. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under grant no. NSF 20-587. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation. Work at Northwestern on the stability of perovskite solar cells was supported by the Office of Naval Research (N00014-20-1-2725). DFT calculations were performed at Institut FOTON as well as Institut des Sciences Chimiques de Rennes, and the work was granted access to the HPC resources of Très Grand Centre de Calcul du CEA (TGCC), the Centre Informatique National de I’Enseignement Supérieur (CINES) and Institut du développement et des ressources en informatique scientifique (IDRIS) under allocations 2019-A0060906724 and 2019-A0070907682 made by Grand Équipement National de Calcul Intensif (GENCI). This research used facilities of the APS, a US Department of Energy Office of Science User Facility operated for the Department of Energy Office of Science by Argonne National Laboratory under contract no. DE−AC02-06CH11357. This research used beamline 11-BM (CMS) of the NSLS-II and the Center for Functional Nanomaterials, both of which are US Department of Energy Office of Science User Facilities operated for the Department of Energy Office of Science by Brookhaven National Laboratory under contract no. DE-SC0012704. We acknowledge the help of B. Chen for supervising the XPS measurements. We thank R. Li for his assistance performing experiments at beamline CMS. The work at Purdue University was supported by the National Science Foundation under grant no. 1724728, CIF21 DIBBs: EI: Creating a Digital Environment for Enabling Data-Driven Science (DEEDS), awarded by the Office of Advanced Cyberinfrastructure.
The authors declare no competing interests.
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Li, W., Sidhik, S., Traore, B. et al. Light-activated interlayer contraction in two-dimensional perovskites for high-efficiency solar cells. Nat. Nanotechnol. (2021). https://doi.org/10.1038/s41565-021-01010-2