The effect of solvent on preparation of CH₃ NH₃ PbI₃ photodetectors via an antisolvent-free method

During the fabrication of lateral-structured photodetectors based on CH₃ NH₃ PbI₃ film, antisolvents represented by toluene are usually used to accelerate the crystallization of perovskite. Using antisolvent not only leads to the formation of shrinkage holes at the bottom of the perovskite layer, but the toxicity of antisolvents would also hinder the industrial preparation of perovskite devices. An antisolvent-free method is a possible solution to avoid these problems. Here, we report a lateral-structured photodetector based on an antisolvent-free method. The lateral photodetector exhibited a high responsivity of 1.75 A⋅W^-1 and specific detectivity (D*) of 3.54 × 10¹² Jones. In particular, the results indicated that the solvent had an influence on perovskite film morphology, crystallization, and device performance. The prepared CH₃ NH₃ PbI₃ film presented needle-like crystals and low performance with single precursor solvent N,N-dimethylformamide (DMF). In comparison, appropriate mixing of dimethyl sulfoxide (DMSO) could improve the morphology, crystallization, and performance of the film. In addition, the solvent volume ratio of the precursor had a profound effect on the performance of the as-prepared photodetectors. At a DMSO:DMF volume ratio of 5:5, the as-prepared film had massive perovskite crystals and fewer defects, resulting in optimal device performance, which can be explained by Urbach energy.