Effect of Annealing Temperature on Film Morphology of Organic–Inorganic Hybrid Pervoskite Solid‐State Solar Cells

Abstract

Organic-inorganic hybrid perovskites have attracted attention as successful light harvesting materials for mesoscopic solid-state solar cells and led to record breaking effi ciencies. The photovoltaic performance of these devices is greatly dependent on the fi lm morphology, which in turn is dependent on the deposition techniques and subsequent treatments employed. In this work the perovskite fi lm is deposited by spin-coating a precursor solution of PbCl 2 and CH 3 NH 3 I (1 to 3 molar ratio) in dimethylformamide. Here, the role of the temperature used in the annealing process required to convert the as deposited solution into the perovskite material is investigated. It is found that the conversion requires suffi ciently high temperatures to ensure the vaporization of solvent and the crystallization of the perovskite material. However, increasing the annealing temperature too high leads to the additional formation of PbI 2 , which is detrimental to the photovoltaic performance. Furthermore, the effect of the annealing temperature on the fi lm formation, morphology, and composition is examined and correlated with the photovoltaic performance and device working mechanisms.

Origin and elimination of photocurrent hysteresis by fullerene passivation in CH3NH3PbI3 planar heterojunction solar cells

“…10), but the decomposition at surfaces or grain boundaries may occur at much lower temperatures. A recent study by M. Grätzel group 25 showed that MAPbI 3 decomposed after thermal annealing for a short time at 150°C, and we found that perovoskites decomposed to PbI 2 at an even lower thermal annealing temperature of 105°C if the thermal annealing duration was as long as 3 h (ref. 26).…”

Ultrasmooth organic–inorganic perovskite thin-film formation and crystallization for efficient planar heterojunction solar cells

“…The above reaction typically involves the evaporation of solvent, sublimation/evaporation of the by-product (CH 3 NH 3 X), crystal nucleation and growth, and so on 28 . As shown in the WAXS study, the anneal time is much shorter for perovskite made from PbAc 2 route than that made from PbCl 2 and PbI 2 routes, which could be correlated to the ease with which the by-product can be removed during perovskite film formation.…”

Efficient hole-blocking layer-free planar halide perovskite thin-film solar cells

“…This is particularly important for the planar cell architecture because an incomplete coverage of a perovskite film results in low-resistance shunting paths and low light absorption in the solar cell. Significant efforts have been developed to improve film coverage and crystalline quality [19][20][21] . We found that the residual organic species or surface-OH basis group absorbed on the FTO substrates have detrimental effects on the formation of smooth perovskite thin films.…”