Elucidation of Formation Mechanism of Bulk Heterojunction Active Layer by Real-Time UV-Visible Absorption and Grazing-lncidence Wide-Angle X-ray Scattering

摘要

The drying process of poly[3-hexylthiophene]:[6,6]-phenyl-C61 -butyric acid methyl ester (P3HT:PCBM) was observed by the real-time measurement of grazing-incidence wide-angle X-ray scattering and ultraviolet-visible absorption for various drying rates. A low drying rate led to high PCBM crystallinity and low P3HT crystallinity. On the other hand, a high drying rate led to low PCBM crystallinity and high P3HT crystallinity. These crystallinities directly affected photovoltaic performance. From these findings, we clarified the fundamental process of the formation of bulk heterojunctions and that drying rate control is an effective method for optimizing the morphology and performance.