Efficient carrier multiplication in CsPbI3 perovskite nanocrystals
Chris de Weerd (Universiteit van Amsterdam)
Leyre Gomez (Universiteit van Amsterdam)
Antonio Capretti (Universiteit van Amsterdam)
Delphine M. Lebrun (Osaka University)
Eiichi Matsubara (Osaka Dental University, Osaka University)
Junhao Lin (Southern University of Science and Technology )
Masaaki Ashida (Osaka University)
Frank C.M. Spoor (TU Delft - Science Education and Communication)
Laurens D.A. Siebbeles (TU Delft - ChemE/Opto-electronic Materials)
Arjan J. Houtepen (TU Delft - ChemE/Opto-electronic Materials)
Kazutomo Suenaga (National Institute of Advanced Industrial Science and Technology (AIST))
Yasufumi Fujiwara (Osaka University)
Tom Gregorkiewicz (Universiteit van Amsterdam, Osaka University)
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Abstract
The all-inorganic perovskite nanocrystals are currently in the research spotlight owing to their physical stability and superior optical properties—these features make them interesting for optoelectronic and photovoltaic applications. Here, we report on the observation of highly efficient carrier multiplication in colloidal CsPbI3 nanocrystals prepared by a hot-injection method. The carrier multiplication process counteracts thermalization of hot carriers and as such provides the potential to increase the conversion efficiency of solar cells. We demonstrate that carrier multiplication commences at the threshold excitation energy near the energy conservation limit of twice the band gap, and has step-like characteristics with an extremely high quantum yield of up to 98%. Using ultrahigh temporal resolution, we show that carrier multiplication induces a longer build-up of the free carrier concentration, thus providing important insights into the physical mechanism responsible for this phenomenon. The evidence is obtained using three independent experimental approaches, and is conclusive.
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