Probing Photocurrent Generation, Charge Transport, and Recombination Mechanisms in Mesostructured Hybrid Perovskite through Photoconductivity Measurements

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• 作者：K谩ri Sveinbj枚rnsson ; Kerttu Aitola ; Xiaoliang Zhang ; Meysam Pazoki ; Anders Hagfeldt ; Gerrit Boschloo ; Erik M. J. Johansson
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2015
• 出版时间：November 5, 2015
• 年：2015
• 卷：6
• 期：21
• 页码：4259-4264
• 全文大小：418K
• ISSN：1948-7185

文摘

Conductivity of methylammonium lead triiodide (MAPbI₃) perovskite was measured on different mesoporous metal oxide scaffolds: TiO₂, Al₂O₃, and ZrO₂, as a function of incident light irradiation and temperature. It was found that MAPbI₃ exhibits intrinsic charge separation, and its conductivity stems from a majority of free charge carriers. The crystal morphology of the MAPbI₃ was found to significantly affect the photoconductivity, whereas in the dark the conductivity is governed by the perovskite in the pores of the mesoporous scaffold. The temperature-dependent conductivity measurements also indicate the presence of states within the band gap of the perovskite. Despite a relatively large amount of crystal defects in the measured material, the main recombination mechanism of the photogenerated charges is bimolecular (band-to-band), which suggests that the defect states are rather inactive in the recombination. This may explain the remarkable efficiencies obtained for perovskite solar cells prepared with wet-chemical methods.