Donor–Acceptor–Acceptor's Molecules for Vacuum-Deposited Organic Photovoltaics with Efficiency Exceeding 9%
Journal
Advanced Energy Materials
Journal Volume
8
Journal Issue
19
Pages
1703603
Date Issued
2018
Author(s)
Abstract
Three vacuum-deposited donor–acceptor–acceptor (d–a–a') small molecule donors are studied with different side chains attached to an asymmetric heterotetracene donor block for use in high efficiency organic photovoltaics (OPVs). The donor with an isobutyl side chain yields the highest crystal packing density compared to molecules with 2-ethylhexyl or n-butyl chains, leading to the largest absorption coefficient and short circuit current in an OPV. It also exhibits a higher fill factor, consistent with its preferred out-of-plane molecular π–π stacking arrangement that facilitates charge transport in the direction perpendicular to the substrate. A power conversion efficiency of 9.3 ± 0.5% is achieved under 1 sun intensity, AM 1.5 G simulated solar illumination, which is significantly higher than 7.5 ± 0.4% of the other two molecules. These results indicate that side chain modification of d–a–a' small molecules offers an effective approach to control the crystal packing configuration, thereby improving the device performance. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Subjects
dipole moment; donors; solar cells
SDGs
Other Subjects
Chains; Dipole moment; Efficiency; Solar cells; Absorption co-efficient; Device performance; Donors; Effective approaches; Organic photovoltaics; Power conversion efficiencies; Side chain modifications; Solar illumination; Molecules
Type
journal article