title: Elucidating double aggregation mechanisms in the morphology optimization of diketopyrrolopyrrole-based narrow bandgap polymer solar cells.
abstract: The power conversion efficiency (PCE) of a DPP-based polymer solar cell is significantly improved by using DIO or DCB as processing additives. The discovery that DCB outperforms DIO with a significantly wider solvent mixture operation window suggests different optimization mechanisms. Although both solvent mixture systems involve double aggregation processes, including a similar solution-to-film aggregation, however, two distinct solution-stage aggregations are observed: relatively amorphous polymer aggregates form in the CF-DIO solution, while more crystalline polymer aggregates form in CF-DCB solution.
authors: Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
authors: Jing
authors: J
authors: Gao
authors: Wei
authors: W
authors: Chen
authors: Letian
authors: L
authors: Dou
authors: Chun-Chao
authors: CC
authors: Chen
authors: Wei-Hsuan
authors: WH
authors: Chang
authors: Yongsheng
authors: Y
authors: Liu
authors: Gang
authors: G
authors: Li
authors: Yang
authors: Y
authors: Yang
keywords: polymer aggregation; polymer crystallization; polymer solar cells; solution-stage morphology; solvent mixtures