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Temperature and Electrical Poling Effects on Ionic Motion in MAPbI 3 Photovoltaic Cells
Author(s) -
Bruno Annalisa,
Cortecchia Daniele,
Chin Xin Yu,
Fu Kunwu,
Boix Pablo P.,
Mhaisalkar Subodh,
Soci Cesare
Publication year - 2017
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201700265
Subject(s) - materials science , poling , energy conversion efficiency , hysteresis , chemical physics , photovoltaic system , ionic bonding , solar cell , diffusion , nanotechnology , chemical engineering , optoelectronics , ion , condensed matter physics , thermodynamics , chemistry , electrical engineering , physics , engineering , organic chemistry , dielectric , ferroelectricity
Despite their excellent power conversion efficiency, MAPbI 3 solar cells exhibit strong hysteresis that hinders reliable device operation. Herein it is shown that ionic motion is the dominant mechanism underlying hysteresis of MAPbI 3 solar cells by studying the effects of electrical poling in different temperature ranges. Complete suppression of the hysteresis below 170 K is consistent with temperature activated diffusion of I − anions and/or the motion of the MA + cations. Ionic motion has important effect on the overall efficiency of the MAPbI 3 solar cells: the initial decrease of the power conversion efficiency while lowering the operating temperature is recovered and even enhanced up to 20% of its original value by applying an electrical poling. The open circuit voltage significantly increases and the current density fully recovers due to the reduction of the electron extraction barrier at the TiO 2 /MAPbI 3 interface driven by the charge accumulation at the interface. Moreover, beside TiO 2 /MAPbI 3 interfacial charge transfer, charge transport in TiO 2 strongly affects the photovoltaic performance, as revealed by MAPbI 3 /ms‐TiO 2 field effect transistors. These results establish the basis to develop effective strategies to mitigate operational instability of perovskites solar cells.