Electrical Heating‐Assisted Multiple Coating Method for Fabrication of High‐Performance Perovskite Fiber Solar Cells by Thickness Control

Abstract Although methods for perovskite morphology and thickness control have significantly improved the power conversion efficiency (PCE) of planar solar cell, they are rarely investigated in the field of fiber solar cell. Electrical heating‐assisted multiple coating, as a solution‐based film process, is proposed for the first time to control perovskite coverage and thickness on metal fiber. It solves the challenges by continuous deposition and hot coating technique. Study of film formation mechanism indicates that adding a drying procedure ensures steady deposition during continuous coating. Continuous deposition feature allows improving film coverage and controlling thickness by simply changing the number of coating times, which differentiate this method from other techniques. In addition, electrical heating is applied to accelerate film formation and perovskite transformation. Thus, a fully covered thin film of perovskite is obtained due to the improved perovskite loading and homogeneity. Corresponding devices achieve a high average PCE of 6.58% with a narrow standard deviation of 0.558. Above that, characterizations demonstrate difficulties in balancing high coverage and appropriate thickness accounts for the wide distribution of PCE and poor reproducibility. It is anticipated this method can move the field toward high efficiency and reproducibility goals.