New Fused Pyrrolopyridine‐Based Copolymers for Organic Solar Cell

Abstract

A fused pyrrolopyridine core having substituents on the nitrogen atom instead of the carbon atom of the indoloindole unit is developed as a new donor unit for organic electronics. The new donor–acceptor copolymers, PDHPHBT, PDHPFBT, and PDHP2FBT, are synthesized using the new donor unit, well‐known benzothiadiazole derivatives containing fluorine atoms as the acceptor. The thermal, optical, and electrochemical properties of these novel copolymers are reported. A solar cell using PDHPFBT with diphenyl ether has an open‐circuit voltage, short‐circuit current, fill factor, and power conversion efficiency of 0.86 V, 11.32 mA cm‐2, 0.59%, and 5.68%, respectively, under AM 1.5G illumination (100 mW cm‐2) in the absence of annealing.

New 3, 8‐difluoro indoloindole‐based copolymers for organic solar cell

“…The newly developed polymers showed a 50 to 60 nm red‐shifted high‐energy π‐π* transition, as well as 80 to 90 nm red‐shifted intramolecular charge transfer bands relative to PDHITHT derivatives. The F atoms introduced on the 3,8‐positions of IDID created a planar backbone due to the intramolecular F‐S interaction 19,23 . Solution, thin film, and 100°C annealed film state absorption spectra for PFDHI‐THT, PFDHI‐TFT, and PFDHI‐T2FT were observed at 437, 613, and 646 nm, 436, 602, and 642 nm, and 433, 593, and 637 nm, respectively (Table 1).…”

“…The F atoms introduced on the 3,8-positions of IDID created a planar backbone due to the intramolecular F-S interaction. 19,23 Solution, thin film, and 100 C annealed film state absorption spectra for PFDHI-THT, PFDHI-TFT, and PFDHI-T2FT were observed at 437, 613, and 646 nm, 436, 602, and 642 nm, and 433, 593, and 637 nm, respectively (Table 1). PFDHI- THT derivatives do not reveal any prominent shoulder peak as compared to PFDHI-TFT and PFDHI-T2FT, probably because of large separation between donor and acceptor due to the absence of F-S interaction.…”

“…Earlier our group had developed an IDID unit via a ring‐fused reaction with bromine at the (2,7‐), and (3, 8‐) positions. The overall efficiency of the device was 5.68%; however, the fill factor (FF) was found to be surprisingly low (FF = 59%) 18,19 . In this study, the major idea was to overcome the pitfalls of the previous work and enhance the FF of the newly developed device.…”

“…The overall efficiency of the device was 5.68%; however, the fill factor (FF) was found to be surprisingly low (FF = 59%). 18,19 In this study, the major idea was to overcome the pitfalls of the previous work and enhance the FF of the newly developed device. Therefore, a new set of IDID donor unit with F substituents was synthesized for organic electronic applications.…”

Unraveling the origin of improved photovoltaic performance in acceptor–acceptor-structured perylene-diimide-based polymeric acceptors through partially fluorinating benzo[c][1,2,5]thiadiazole

“…Synthesis processes of the selected electron-deficient BTbased bistin comonomers 4,7-di(5-(trimethylstannyl)thienyl-2yl)benzo[c][1,2,5]thiadiazole (DTBTSn) and monofluorinated 4,7-di(5-(trimethylstannyl)thienyl-2-yl)-5-fluorobenzo[c][1,2,5]thiadiazole (DTFBTSn) were obtained according to a previously reported method (Scheme S1, ESI †). 56 To ensure enough solubility and solution-processability, large branched fatty primary amine 2-octyldodecylamine (NH 2 -OD) was selected and obtained via a Gabriel reaction in 76% yield, 57 and dibromide PDI-ODBr 2 was prepared according to a similar method with the yield of 39% 28 (Scheme S2, ESI †). Chemical structures for all intermediates and comonomers were characterized and verified by 1 H NMR, 13 C NMR (Fig.…”