Abstract
Emerging metal-halide perovskites (MHPs) have shown advanced charge transport properties suitable for application in solar cells, photodetectors, and many more. While the past decade witnessed tremendous progress in MHPs, very little is known about the origin of defects and their effect on carrier lifetime. In this study, we compare hybrid and all-inorganic MHPs prepared by inverse temperature solution and high-temperature melt growth to explore the influence of material preparation on the formation of defects. The presence of a low concentration of vacancies was shown in all MHPs regardless of their synthesis method demonstrated by the interaction of positron particles with vacancies and lattices of MHPs and explained by ab initio simulation of positron annihilation. We combined the Raman, Fourier transform infrared (FTIR), and positron annihilation spectroscopy methods to establish the nature of imperfections in MHPs grown using different methods. Our Raman and FTIR results reveal that only the solution-grown crystals are prone to the incorporation of a solvent in bulk during synthesis. In vast majority of studies, the charge carrier lifetime is explored using photoluminescence (PL) spectroscopy as it is a readily available method. However, PL is very sensitive to both bulk and surface recombination phenomena. Combining current waveform time-of-flight and time-resolved photoluminescence spectroscopy methods, the bulk recombination differs by a factor of 2 from crystals grown by solution versus high-temperature melt. The results propose that solvent trapping matters, not intrinsic defects. The study also suggests potential pathways for further improvement of hybrid and all-inorganic MHPs.
| Original language | English |
|---|---|
| Pages (from-to) | 297-306 |
| Number of pages | 10 |
| Journal | Chemistry of Materials |
| Volume | 34 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 11 2022 |
Funding
A.M., J.P., P.P, M.B., and E.B. acknowledge financial support from the Grant Agency of the Czech Republic, Grant No. P102/19/11920S and the Grant Agency of Charles University, projects No. 1234119 and 379621. A.M. thanks Helmholtz-Zentrum Berlin for support and acknowledges financial support from the German Science Foundation (DFG) in the framework of the priority program “Perovskite Semiconductors: From Fundamental Properties to Devices” (SPP 2196). H.E. thanks the Ministry of Education, Youth, and Sports of the Czech Republic – National Program of Sustainability (NPU LO1305). Computational resources were supplied by the project ″e-Infrastruktura CZ″ (e-INFRA LM2018140) provided within the program Projects of Large Research, Development, and Innovations Infrastructures. A.K. gratefully acknowledges Prof. Fochuk P.M. and Dr. Khalavka Y.B. for support. K.H., B.D., E.L., B.H., and M.A. acknowledge financial support from U.S. Department of Homeland Security (grant # 2016-DN-077-ARI01). We are grateful to Prof. Sergei V Kalinin for insightful comments on the manuscript.