Annealing Heat Treatment of Organic Material for Controlled Bulk Heterojunction Solar Cells

Abstract

The morphology of active layers of organic solar cells plays crucial roles in achieving good performing devices with longer life span. The process of fabricating these devices involved post deposition thermal annealing, which increases the crystallinity and enhances phase-separated domains of deposited active layer components. A blended composite of regioregular poly(3- hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) is used as the active layer in this BHJ solar cell. In this work, the blends were prepared for different ratio of P3HT: PCBM and annealed at different temperatures. A variety of experimental techniques were employed to observe the microstructures of various active layers at different domains after quenching to room temperature. A better understanding of the correlation between the observed microstructures and electrical characteristic of the active layers is therefore used to explain the performance of organic solar cells.