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Thermal stress analysis of mesoporous perovskite solar cell by finite element method

For nearly five years, the photoelectric conversion efficiency of the perovskite-based solar cells are extraordinarily developed at a high speed, showing a good application prospect. It is necessary to further optimize the devices and make them industrially feasible. The different temperature requirements of perovskite solar cells during the preparation process will result in undesirable thermal stresses. There have already existed a number of papers concerning methods to improve power conversion efficiency of perovskite-based solar cell. However, the thermal properties of laminated structure of solar cell, which significantly affect the long-time reliability of solar cell packaging, have rarely been discussed. Different temperature loads in preparation process are taken into account to obtain the resulting thermal stresses in this paper. The fabrication processing is reproduced in FEM simulations which are able to directly analyze the internal stresses within and between solar cell layers. The goal is to develop a systematic understanding of thermal behavior of perovskite solar cell during the fabrication process. The study figures out that the maximum Mises stresses are located in central area for the upper layers. But the maximum stress on the bottom layer occurs at the fringe of the etching groove. The large accumulated plastic strain at the center will cause a crack initiation at this location and then the crack may continue to grow to the etching groove or even cause delamination. Due to the mismatch of the coefficient of thermal expansion, warpage is evident for alumina film and molybdenum oxide film, which had a bad influence on the uniformity of the following encapsulation process. It is meaningful to provide a reference for the continuous improvement of efficiency. The encapsulation of perovskite-based solar cells also will be discussed to reduce the resulting internal loads to a minimum value.