材料科学
聚合物
钙钛矿(结构)
薄膜
图层(电子)
带隙
化学工程
氧烷
光电子学
吸收(声学)
纳米技术
复合材料
谱线
天文
工程类
物理
作者
Sangmin Chae,Ahra Yi,Hyo Jung Kim
标识
DOI:10.1016/j.mtener.2019.100341
摘要
Along with the development of perovskite materials, which have enormous potential for optoelectronics such as solar cells and light-emitting diode devices, numerous organic semiconductor polymers, which have been critically adopted into the hole and electron transporting layers, have been synthesized and studied. In n–i–p-structured perovskite solar cells, various outstanding polymer materials have been successfully applied. However, in p–i–n-structured solar cells, the hydrophobic nature of the polymers makes the sequential deposition of a perovskite thin film difficult. Several destructive methods have been proposed; however, a more efficacious and fundamental method is urgently needed. Here, we present a nondestructive polymer hole-transporting layer (HTL) thin-film formation process based on molecular engineering via a simple solvent process. When we used various solvents with different volatilities, perovskite film formation was achieved on polymer thin films formed from highly volatile solvents. In addition, we elucidated the structure and orientation of the molecules in the films and revealed that the molecular structure of face-on orientation for the horizontally aligned hydrophobic alkyl groups induced a lower surface energy of the film, as determined by grazing-incidence wide-angle X-ray scattering (GIWAXS) measurements. Furthermore, the tilt angle of the molecules, which was calculated from the results of quantitative near-edge X-ray absorption fine structure (NEXAFS) analysis, was found to correlate with the surface energy. This result provides guidance for polymer-orientation and surface-energy studies, and perovskite solar cells fabricated using the polymer HTL demonstrated good durability and flexibility. We expect that our approach represents a new route for fabricating p–i–n-structured solar cells and that numerous valuable p-type conjugated polymers will be developed via our proposed molecular engineering process.
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