Multistep Photoluminescence Decay Reveals Dissociation of Geminate Charge Pairs in Organolead Trihalide Perovskites |
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| Authors: | Ramūnas Augulis Marius Franckevi?ius Vytautas Abramavi?ius Darius Abramavi?ius Shaik Mohammed Zakeeruddin Michael Grätzel Vidmantas Gulbinas |
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| Affiliation: | 1. Center for Physical Sciences and Technology, Vilnius, Lithuania;2. Department of Theoretical Physics, Faculty of Physics, Vilnius University, Vilnius, Lithuania;3. Laboratory of Photonics and Interfaces, ISIC, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland |
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| Abstract: | Charge carrier dynamics in organolead iodide perovskites is analyzed by employing time‐resolved photoluminescence spectroscopy with several ps time resolution. The measurements performed by varying photoexcitation intensity over five orders of magnitude enable separation of photoluminescence components related to geminate and nongeminate charge carrier recombination and to address the dynamics of an isolated geminate electron–hole pair. Geminate recombination dominates at low excitation fluence and determines the initial photoluminescence decay. This decay component is remarkably independent of the material structure and experimental conditions. It is demonstrated that dependences of the geminate and nongeminate radiative recombination components on excitation intensity, repetition rate, and temperature, are hardly compatible with carrier trapping and exciton dissociation models. On the basis of semiclassical and quantum mechanical numerical calculation results, it is argued that the fast photoluminescence decay originates from gradual spatial separation of photogenerated weakly bound geminate charge pairs. |
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| Keywords: | charge carriers methylammonium lead iodide perovskites photoluminescence solar cells |
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