AC transport properties of Nanocrystalline CsPbBr3

Gennaro Conte 

Rome, University "Roma Tre" (DIE), Roma 00146, Italy

Abstract

CsPbBr3 produced by co-evaporating CsBr and PbBr2 purified powders are attracting much interest for their interesting optical characteristics. Indeed, nanocrystallites are produced in the thin films as evidenced by optical spectroscopy and X-ray diffraction. These nanoaggregates are wide-gap semiconductors with direct band-to-band transition. Identification of the nanocrystallites in the film is based on a similarity of the observed spectroscopic properties with those of the bulk CsPbBr3 purified by the Bridgman technique. The materials object of this study have been deposited by PVD inside an UHV apparatus. These materials show an exciton absorption also at RT. The FWHM of the exciton peak has been used to evaluate, together with X-ray analysis, the quality of the deposited material. The paper reports on the AC transport properties investigated by admittance spectroscopy techniques in a wide frequency and temperature range aimed to identify the role of the surface located defects. AC electrical measurements have been carried out in the 0.1 Hz-10 kHz range by using a Solartron 1250 FRA equipped with a 1296A dielectric interface, whereas a HP4192A LF impedance analyzer has been used in the 10 kHz-10 MHz range. Results show as the Fermi level is pinned by the surface states which induce an electron accumulation layer at the crystallites' surface influencing the current transport at lower and intermediate temperature while, at the higher, an activate transport mechanism is found. The possibility to apply the time-temperature superposition principle gives the opportunity to present and discuss the results as a function of the f and T on the basis of master curves obtained by normalizing f to the most probable hopping frequency.

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Presentation: Poster at E-MRS Fall Meeting 2006, Symposium A, by Gennaro Conte
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-02-27 15:43
Revised:   2009-06-07 00:44
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