%0 Journal Article %A Steyrleuthner, Robert %A Schubert, Marcel %A Howard, Ian %A Klaumünzer, Bastian %A Schilling, Kristian %A Chen, Zhihua %A Saalfrank, Peter %A Laquai, Frédéric %A Facchetti, Antonio %A Neher, Dieter %D 2012 %T Aggregation in a High-Mobility n‑Type Low-Bandgap Copolymer with Implications on Semicrystalline Morphology %U https://acs.figshare.com/articles/journal_contribution/Aggregation_in_a_High_Mobility_n_Type_Low_Bandgap_Copolymer_with_Implications_on_Semicrystalline_Morphology/2471278 %R 10.1021/ja306844f.s001 %2 https://acs.figshare.com/ndownloader/files/4113979 %K UV %K quantum chemical calculations %K film formation %K Analytical ultracentrifugation measurements %K chain collapse %K PL %K polymer chain %K aggregation phenomena %K NMR measurements %K solution %K Semicrystalline MorphologyWe %K polymer chains %X We explore the photophysics of P­(NDI2OD-T2), a high-mobility and air-stable n-type donor/acceptor polymer. Detailed steady-state UV–vis and photoluminescence (PL) measurements on solutions of P­(NDI2OD-T2) reveal distinct signatures of aggregation. By performing quantum chemical calculations, we can assign these spectral features to unaggregated and stacked polymer chains. NMR measurements independently confirm the aggregation phenomena of P­(NDI2OD-T2) in solution. The detailed analysis of the optical spectra shows that aggregation is a two-step process with different types of aggregates, which we confirm by time-dependent PL measurements. Analytical ultracentrifugation measurements suggest that aggregation takes place within the single polymer chain upon coiling. By transferring these results to thin P­(NDI2OD-T2) films, we can conclude that film formation is mainly governed by the chain collapse, leading in general to a high aggregate content of ∼45%. This process also inhibits the formation of amorphous and disordered P­(NDI2OD-T2) films. %I ACS Publications