TY - JOUR
T1 - Asymmetrical side-chain engineering of small-molecule acceptors enable high-performance nonfullerene organic solar cells
AU - Kan, Bin
AU - Chen, Xuebin
AU - Gao, Ke
AU - Zhang, Ming
AU - Lin, Francis
AU - Peng, Xiaobin
AU - Liu, Feng
AU - Jen, Alex K-Y.
PY - 2020/1
Y1 - 2020/1
N2 - Three new small molecules based on the benzo [1,2-b:4,5-b’]dithiophene (BDT) fused central core with different side-chains, namely DPBDT-4Cl, POBDT-4Cl and COBDT-4Cl, are designed and synthesized to investigate the side-chain effect on the properties of nonfullerene acceptors. DPBDT-4Cl has symmetrical phenylalkyl side-chains on the central BDT unit. In order to narrow the bandgap and reduce the steric hindrance, the phenylalkyl chains are systematically replaced with the flexible electron-donating alkoxy side-chain (POBDT-4Cl) and alkyl side-chain (COBDT-4Cl). As a result, POBDT-4Cl and COBDT-4Cl are characterized with asymmetry-featured side-chains. From DPBDT-4Cl to POBDT-4Cl to COBDT-4Cl, their light absorption abilities, molecular packing behaviors and crystallinity are gradually enhanced. The devices based on these three acceptors all show power conversion efficiencies (PCEs) over 11% with energy loss below 0.55 eV. Compared to DPBDT-4Cl, POBDT-4Cl and COBDT-4Cl obviously exhibit enhanced device performance with improved short-circuit current densities (Jsc) and fill factors (FFs), which mainly ascribe to their reduced charge recombination and enhanced charge transport. In addition, the COBDT-4Cl achieved a high efficiency of 13.5% with a Jsc of 21.8 mA cm−2 and an FF of 0.71. This result is among the best performance obtained from asymmetry-featured small molecules.
AB - Three new small molecules based on the benzo [1,2-b:4,5-b’]dithiophene (BDT) fused central core with different side-chains, namely DPBDT-4Cl, POBDT-4Cl and COBDT-4Cl, are designed and synthesized to investigate the side-chain effect on the properties of nonfullerene acceptors. DPBDT-4Cl has symmetrical phenylalkyl side-chains on the central BDT unit. In order to narrow the bandgap and reduce the steric hindrance, the phenylalkyl chains are systematically replaced with the flexible electron-donating alkoxy side-chain (POBDT-4Cl) and alkyl side-chain (COBDT-4Cl). As a result, POBDT-4Cl and COBDT-4Cl are characterized with asymmetry-featured side-chains. From DPBDT-4Cl to POBDT-4Cl to COBDT-4Cl, their light absorption abilities, molecular packing behaviors and crystallinity are gradually enhanced. The devices based on these three acceptors all show power conversion efficiencies (PCEs) over 11% with energy loss below 0.55 eV. Compared to DPBDT-4Cl, POBDT-4Cl and COBDT-4Cl obviously exhibit enhanced device performance with improved short-circuit current densities (Jsc) and fill factors (FFs), which mainly ascribe to their reduced charge recombination and enhanced charge transport. In addition, the COBDT-4Cl achieved a high efficiency of 13.5% with a Jsc of 21.8 mA cm−2 and an FF of 0.71. This result is among the best performance obtained from asymmetry-featured small molecules.
KW - Asymmetrical
KW - Benzo[1,2-b:4,5-b’]dithiophene
KW - Side-chains
KW - Small-molecule acceptors
UR - http://www.scopus.com/inward/record.url?scp=85074422591&partnerID=8YFLogxK
UR - https://www.scopus.com/record/pubmetrics.uri?eid=2-s2.0-85074422591&origin=recordpage
U2 - 10.1016/j.nanoen.2019.104209
DO - 10.1016/j.nanoen.2019.104209
M3 - RGC 21 - Publication in refereed journal
SN - 2211-2855
VL - 67
JO - Nano Energy
JF - Nano Energy
M1 - 104209
ER -
