Enabling full-scale grain boundary mitigation in polycrystalline perovskite solids

There exists a considerable density of interaggregate grain boundaries (GBs) and intra-aggregate GBs in polycrystalline perovskites. Mitigation of intra-aggregate GBs is equally notable to that of interaggregate GBs as intra-aggregate GBs can also cause detrimental effects on the photovoltaic performances of perovskite solar cells (PSCs). Here, we demonstrate full-scale GB mitigation ranging from nanoscale intra-aggregate to submicron-scale interaggregate GBs, by modulating the crystallization kinetics using a judiciously designed brominated arylamine trimer. The optimized GB-mitigated perovskite films exhibit reduced nonradiative recombination, and their corresponding mesostructured PSCs show substantially enhanced device efficiency and long-term stability under illumination, humidity, or heat stress. The versatility of our strategy is also verified upon applying it to different categories of PSCs. Our discovery not only specifies a rarely addressed perspective concerning fundamental studies of perovskites at nanoscale but also opens a route to obtain high-quality solution-processed polycrystalline perovskites for high-performance optoelectronic devices.
This work was financially supported by Beijing Natural Science Foundation (JQ21005), the National Key R&D Program of China (2021YFB3800100 and 2021YFB3800101), the National Natural Science Foundation of China (91733301 and 62104221), the China Postdoctoral Science Foundation (2020M670036), and the R&D Fruit Fund (20210001). M.G. and S.M.Z. thank the King Abdulaziz City for Science and Technology (KACST) for financial support. M.I.D. acknowledges funding from the Royal Society. N.A. and R.H.F. thank the EPSRC project SUNRISE (EP/P032591/1). Q.H. and T.P.R. were supported by the U.S. Office of Naval Research under contract N00014-17-1-2241. Q.H. thanks the support from USTC Research funds of the Double First-Class Initiative (YD2100002007). We thank the support for sample preparation at Molecular Foundry of Lawrence Berkeley National Laboratory (LBNL), which is supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under contract no. DE-AC02-05CH11231. We also acknowledge the GIXD measurements at beamline 7.3.3 of Advanced Light Source (LBNL), which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. P.T. and J.A. acknowledge the funding from Generalitat de Catalunya 2017 SGR 327 and the Spanish MINECO project ENE2017-85087-C3. ICN2 is supported by the Severo Ochoa program from Spanish MINECO (grant no. SEV-2017-0706) and is funded by the CERCA Programme/Generalitat de Catalunya.