Crystallinity control of the halide perovskite thin-film via solution shearing process

Abstract

The printable electronics field is emerging as a process for next-generation devices as it has the advantage of being light, flexible, and capable of large-area production at a relatively low price. However, there is a problem in that performance and uniformity are lowered due to a lack of control technology in the process of printing electronic materials. In the case of low-dimensional materials, their spacing or alignment is important, and in most materials, their crystallinity is important. Several printing technologies using rolls, sprays, meniscus, etc. have been developed, but among them, the solution shearing process requires less solution consumption, freedom of choice, and advantageous features for large-area crystallization, forming a high-quality thin film over a large area. Halide perovskite-based thin-film solar cells are a typical field that requires large-area and high-quality thin films. First, the changes in the morphology of the thin film according to the substrate temperature and coating speed, which are the most important variables, were mapped and the crystallization mechanism was studied. The role and importance of thickness and crystallinity were identified through the device fabrication. Next, to optimize both properties of thickness and crystallinity at the same time, the blade surface treatment, which was used only to prevent contamination, was applied to control the meniscus. The surface treatment of the blade controlled only the thickness and crystallite size of the thin film and did not affect the degree of orientation according to the speed, so each property could be optimized. As a result, the performance of the solar cell was further improved.