Interpretation of the Biphasic Charge Carrier Recombination Process Observed in Mesoporous-Structured Perovskite Solar Cells
Hao-Yi Wang a, Yi Wang a b, Man Yu a, Yujun Qin a, Xi-Cheng Ai a, Jian-Ping Zhang a
a Department of Chemistry, Renmin University of China, Beijing 100872, P. R. China
b Department of Chemistry, National University of Singapore, 21 Lower Kent Ridge Road, Singapore, 119077, Singapore
NIPHO
Proceedings of International Conference on Perovskite Thin Film Photovoltaics, Photonics and Optoelectronics (ABXPV18PEROPTO)
Perovskite Thin Film Photovoltaics (ABXPV18). 27-28 Feb
Rennes, France, 2018 February 27th - March 1st
Organizer: Jacky Even
Oral, Hao-Yi Wang, presentation 023
DOI: https://doi.org/10.29363/nanoge.abxpvperopto.2018.023
Publication date: 11th December 2017

Organic-inorganic perovskite solar cells have surged great waves in photovoltaic field owing to their peculiar advantages. At the state-of-the-art, the mesoporous-structured perovskite solar cells (MPSCs) hold the efficiency record, and have already exceeded 22%. In our work, the charge carrier recombination dynamics of MPSCs are investigated by transient photovoltage decay methods. A biphasic charge carrier recombination process is observed, i.e., at low quasi-Fermi level, photo-generated electrons predominately populate in perovskite phase, while at high quasi-Fermi level, most electrons occupy traps in mesoporous TiO2, and then the charge carrier recombination process is determined by the two different phases, respectively.[1] This phenomenon is observed according to the different trap-states distributions of the perovskite and meso-TiO2 phases in MPSCs. Further investigation suggests that the biphasic charge carrier recombination process is also influenced by the trap-states density, especially the density of perovskite phases, under the assistance of temperature-dependent fluorescence.[2] Considering that MPSCs are initially originated from DSSCs, and the structures of the two devices are highly similar with each other. The charge carrier recombination processes of the conventional DSSCs and MPSCs are compared, a novel physical model based on multiple-trapping theory is proposed by taking into account both the contributions of perovskite phase and mesoporous TiO2 phase, which is suitable to describe the biphasic charge carrier recombination process in MPSCs.[3] These findings provide an innovative horizon for the understanding of the charge carrier recombination process in perovskite solar cells.

 

 

[1] H. Y. Wang, Y. Wang, M. Yu, J. Han, Z. X. Guo, X. C. Ai, J. P. Zhang and Y. Qin, Phys. Chem. Chem. Phys. 2016, 18, 12128-12134.

[2] H. Y. Wang, M. Y. Hao, J. Han, M. Yu, Y. Qin, P. Zhang, Z. X. Guo, X. C. Ai and J. P. Zhang, Chem. Eur. J. 2017, 23, 3986-3992.

[3] H. Y. Wang, Y. Wang, M. Y. Hao, Y. Qin, L. M. Fu, Z. X. Guo, X. C. Ai and J. P. Zhang, ChemSusChem 2017, 10.1002/cssc.201701780.

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