Here, we examine grain boundaries (GBs) with respect to non-GB regions (grain surfaces (GSs) and grain interiors (GIs)) in high-quality micrometer-sized perovskite CH3NH3PbI3 (or MAPbI3) thin films using high-resolution confocal fluorescence-lifetime imaging microscopy in conjunction with kinetic modeling of charge-transport and recombination processes. We show that, contrary to previous studies, GBs in our perovskite MAPbI3 thin films do not lead to increased recombination but that recombination in these films happens primarily in the non-GB regions (i.e., GSs or GIs). We also find that GBs in these films are not transparent to photogenerated carriers, which is likely associated with a potential barrier at GBs. Even though GBs generally display lower luminescence intensities than GSs/GIs, the lifetimes at GBs are no worse than those at GSs/GIs, further suggesting that GBs do not dominate non-radiative recombination in MAPbI3 thin films.
Bibliographical noteFunding Information:
The work at the National Renewable Energy Laboratory was supported by the U.S. Department of Energy under Contract no. DE-AC36-08GO28308. KZ and DK acknowledge the support from the U.S. Department of Energy SunShot Initiative under the Next Generation Photovoltaics 3 program (DE-FOA-0000990). YZ acknowledges the support on the FLIM instrumentation by the BioEnergy Science Center (BESC), a DOE Bioenergy Research Center funded by the Office of Biological and Environmental Research (BER) in the DOE Office of Science. JvdL acknowledges the support from the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences (DOE). MY and ZL acknowledge the support by the hybrid perovskite solar cell program of the National Center for Photovoltaics funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Solar Energy Technologies Office.
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ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry