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Here in, we have designed two new unfused non‐fullerene small molecules using asymmetric benzo[1,2‐b:3.4‐b′, 6,5‐b"]trithiophene (BTT) as the central donor core and different terminal units i. e., 2‐(3‐oxo‐2,3‐dihydro‐1H‐inden‐1‐ylidene)malononitrile (NFA‐4) and 1,3‐diethyl‐2‐thioxodi hydropyrimidine‐4,6 (1H,5H)‐dione (NFA‐5) and examined their optical and electrochemical properties. Using a wide band‐gap copolymer D18, organic solar cells (OSCs) based on bulk heterojunction of D18:NFA‐4 and D18:NFA‐5 showed overall power conversion efficiency (PCE) of about 17.07 % and 11.27 %, respectively. The increased PCE for the NFA‐4‐based OSC, compared to NFA‐5 counterpart, is due higher value of short circuit current (JSC), open circuit voltage (VOC), and fill factor (FF). Following the addition of small amount of NFA‐5 to the binary bulk heterojunction D18:NFA‐4, the ternary organic solar cells attained a PCE of 18.05 %, surpassing that of the binary counterparts due to the higher values of which is higher than that for the binary counterparts and attributed to the increased values of JSC, FF, and VOC. The higher value of JSC is linked to the efficient use to excitons transferred from NFA‐5 to NFA‐4 with a greated dipole moment than NFA‐5 and subsequently dissociated into a free charge carrier efficiently. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel D-A1-D-A2 copolymer denoted as P1 containing two electron withdrawing units based on benzothiadiazole (BT) and 9-(2-octyldodecyl)−8H-pyrrolo[3,4-b] bisthieno[2,3-f:3′,2′-h]quinoxaline-8,10(9H)-dione (PTQD) units was synthesized and characterized. The resulting copolymer exhibits a broad-absorption spectrum, relatively deep lying HOMO energy level (−5.44 eV) and narrow optical bandgap (1.50 eV). Bulk heterojunction (BHJ) polymer solar cells (PSCs) based on P1 as donor and PC71BM as acceptor with optimized donor to acceptor weight ratio of 1:2 and processed with DIO/CB solvent showed good photovoltaic performance with power conversion efficiency of 6.21% which is higher than that of the device processed without solvent additive (4.40%). The absorption and morphology investigations of the active layers indicated that structural and morphological changes were induced by the solvent additive. This higher power conversion efficiency could be mainly attributed to the absorption enhancement and improved charge transported in the active layer induced by the better nanoscale morphology of the active layer. This study demonstrated that a copolymer with two different acceptor moieties in the backbone may be promising candidate as donor copolymer for solution processed BHJ PSCs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 155-168 [ABSTRACT FROM AUTHOR]

Here in, we have designed two new unfused non-fullerene small molecules using asymmetric benzo[1,2-b:3.4-b', 6,5-b"]trithiophene (BTT) as the central donor core and different terminal units i. e., 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (NFA-4) and 1,3-diethyl-2-thioxodi hydropyrimidine-4,6 (1H,5H)-dione (NFA-5) and examined their optical and electrochemical properties. Using a wide band-gap copolymer D18, organic solar cells (OSCs) based on bulk heterojunction of D18:NFA-4 and D18:NFA-5 showed overall power conversion efficiency (PCE) of about 17.07 % and 11.27 %, respectively. The increased PCE for the NFA-4-based OSC, compared to NFA-5 counterpart, is due higher value of short circuit current (J SC ), open circuit voltage (V OC ), and fill factor (FF). Following the addition of small amount of NFA-5 to the binary bulk heterojunction D18:NFA-4, the ternary organic solar cells attained a PCE of 18.05 %, surpassing that of the binary counterparts due to the higher values of which is higher than that for the binary counterparts and attributed to the increased values of J SC , FF, and V OC . The higher value of J SC is linked to the efficient use to excitons transferred from NFA-5 to NFA-4 with a greated dipole moment than NFA-5 and subsequently dissociated into a free charge carrier efficiently., (© 2024 Wiley-VCH GmbH.)