title: P3HT:DiPBI bulk heterojunction solar cells: morphology and electronic structure probed by multiscale simulation and UV/vis spectroscopy.
abstract: Coarse grained molecular dynamics simulations are performed for a mixture of poly(3-hexylthiophene) (P3HT) and diperylene bisimide (DiPBI). The effect of different annealing and cooling protocols on the morphology is investigated and the resulting domain structures are analyzed. In particular, π-stacked clusters of DiPBI molecules are observed whose size decreases with increasing temperature. Domain structure and diffusivity data suggest that the DiPBI subsystem undergoes an order → disorder phase transition between 700 and 900 K. Electronic structure calculations based on density functional theory are carried out after backmapping the coarse grained model onto an atomistic force field representation built upon first principles. UV/vis absorption spectra of the P3HT:DiPBI mixture are computed using time-dependent density functional linear response theory and recorded experimentally for a spin-coated thin film. It is demonstrated that the absorption spectrum depends sensitively on the details of the amorphous structure, thus providing valuable insight into the morphology. In particular, the results show that the tempering procedure has a significant influence on the material's electronic properties. This knowledge may help to develop effective processing routines to enhance the performance of bulk heterojunction solar cells.
authors: Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster and Center for Multiscale Theory & Computation, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany. t.winands@wwu.de.
authors: Thorsten
authors: T
authors: Winands
authors: Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster and Center for Multiscale Theory & Computation, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany. t.winands@wwu.de.
authors: Marcus
authors: M
authors: Böckmann
authors: Institut für Angewandte Physik, Westfälische Wilhelms-Universität Münster, Corrensstr. 2/4, 48149 Münster, Germany.
authors: Thomas
authors: T
authors: Schemme
authors: Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster and Center for Multiscale Theory & Computation, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany. t.winands@wwu.de.
authors: Phong-Minh Timmy
authors: PM
authors: Ly
authors: Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster and Center for Multiscale Theory & Computation, Corrensstr. 28/30, 48149 Münster, Germany.
authors: Djurre H
authors: DH
authors: de Jong
authors: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences Beijing, 100190, P. R. China.
authors: Zhaohui
authors: Z
authors: Wang
authors: Institut für Angewandte Physik, Westfälische Wilhelms-Universität Münster, Corrensstr. 2/4, 48149 Münster, Germany.
authors: Cornelia
authors: C
authors: Denz
authors: Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster and Center for Multiscale Theory & Computation, Corrensstr. 28/30, 48149 Münster, Germany.
authors: Andreas
authors: A
authors: Heuer
authors: Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster and Center for Multiscale Theory & Computation, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany. t.winands@wwu.de.
authors: Nikos L
authors: NL
authors: Doltsinis