Citation:
Sezen , H , Shang , H , Bebensee , F , Yang , C , Buchholz , M , Nefedov , A , Heissler , S , Carbogno , C , Scheffler , M , Rinke , P & Wöll , C 2015 , ' Evidence for photogenerated intermediate hole polarons in ZnO ' , Nature Communications , vol. 6 , 6901 , pp. 1-4 . https://doi.org/10.1038/ncomms7901
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Abstract:
Despite their pronounced importance for oxide-based photochemistry, optoelectronics and photovoltaics, only fairly little is known about the polaron lifetimes and binding energies. Polarons represent a crucial intermediate step populated immediately after dissociation of the excitons formed in the primary photoabsorption process. Here we present a novel approach to studying photoexcited polarons in an important photoactive oxide, ZnO, using infrared (IR) reflection–absorption spectroscopy (IRRAS) with a time resolution of 100 ms. For well-defined (10-10) oriented ZnO single-crystal substrates, we observe intense IR absorption bands at around 200 meV exhibiting a pronounced temperature dependence. On the basis of first-principles-based electronic structure calculations, we assign these features to hole polarons of intermediate coupling strength.
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