New D-A-A’-Configured Small Molecule Donors Employing Conjugation to Red-shift the Absorption for Photovoltaics
Journal
Chemistry - An Asian Journal
Journal Volume
15
Journal Issue
16
Pages
2520-2531
Date Issued
2020
Author(s)
Abstract
Four new donor-acceptor-acceptor’ (D-A-A’)-configured donors, CPNT, DCPNT, CPNBT, and DCPNBT equipped with naphtho[1,2-c:5,6-c′]bis([1,2,5]-thiadiazole) (NT) or naphtho[2,3-c][1,2,5]thiadiazole (NBT) as the central acceptor (A) unit bridging triarylamine donor (D) and cyano or dicyanovinylene acceptor (A’), were synthesized and characterized. All molecules exhibit bathochromic absorption shifts as compared to those of the benzothiadiazole (BT)-based analogues owing to improved electron-withdrawing and quinoidal character of NT and NBT cores that lead to stronger intramolecular charge transfer. Favorable energy level alignments with C70, together with the good thermal stability and the antiparallel dimeric packing render CPNT and DCPNT suitable donors for vacuum-processed organic photovoltaics (OPV)s. OPVs based on DCPNT : C70 active layers displayed the best power conversion efficiency (PCE)=8.3%, along with an open circuit voltage of 0.92 V, a short circuit current of 14.5 mA cm−2 and a fill factor of 62% under 1 sun intensity, simulated AM1.5G illumination. Importantly, continuous light-soaking with AM 1.5G illumination has verified the durability of the devices based on CPNT:C70 and DCPNT : C70 as the active blends. The devices were examined for their feasibility of indoor light harvesting under 500 lux illumination by a TLD-840 fluorescent lamp, giving PCE=12.8% and 12.6%, respectively. These results indicate that the NT-based D-A-A’-type donors CPNT and DCPNT are potential candidates for high-stability vacuum-processed OPVs suitable for indoor energy harvesting. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Subjects
indoor photovoltaic; organic photovoltaic; small molecule donor; vacuum process
SDGs
Other Subjects
Charge transfer; Energy harvesting; Molecules; Open circuit voltage; Organic compounds; Bathochromic absorption; Benzothiadiazoles; Continuous light; Electronwithdrawing; Energy level alignment; Intra-molecular charge transfer; Organic photovoltaics; Power conversion efficiencies; Red Shift
Type
journal article