Abstract
An electron acceptor with a truxene core and ring-fusion perylene diimide (PDI) tripolymer annulated by selenium (Se) branch, named as FTr-3PDI-Se, is designed and synthesized. FTr-3PDI-Se exhibits large conjugated planar conformation, strong absorption spectra in the regions of 300–400 and 450–550 nm, the deep HOMO energy level of 6.10 eV, and high decomposition temperature above 400°C. The FTr-3PDI-Se: PBDB-T-2Cl based device achieved a disappointing power conversion efficiency (PCE) of 1.6% together with a high Voc of 1.12 V. The low PCE was due to the large aggregates of blend film, the imbalanced hole/electron transport and low PL quenching efficiencies. The high Voc can be attributed to the high-lying LUMO level of FTr-3PDI-Se and the low-lying HOMO level of PBDB-T-2Cl. Our research presents an interesting and effective molecule-designing method to develop non-fullerene acceptor.
Highlights
Organic solar cells (OSCs) have attracted boundless interest over the past few decades owing to the advantages of light weight, low cost, wide source, and large-scale roll-to-roll printing process (Kang et al, 2016; Hou et al, 2018)
Inspired by the above achievements of Se-annulated perylene diimide (PDI), we report the design and synthesis of truxene functionalized star-shaped non-fullerene acceptors (NFAs) with fused selenium-annulated PDIs, named FTr-3PDI-Se (Scheme 1)
The FTr-3PDI-Se exhibited large conjugated planar skeleton that can effectively promote the blend films to form large aggregates, which may lead to bimolecular recombination, limiting the OSCs performance
Summary
Organic solar cells (OSCs) have attracted boundless interest over the past few decades owing to the advantages of light weight, low cost, wide source, and large-scale roll-to-roll printing process (Kang et al, 2016; Hou et al, 2018). Oxidative ring-fusion between the central aromatic core and the PDI branches was verified to be an effective strategy to achieve an exquisite balance aforesaid for high OSCs performance The five-membered heteroatom-annulated PDI NFAs reinforced intra- and intermolecular interactions, leading to high electron mobility, which achieved improved PCEs. Among the varied nitrogen/chalcogen, the selenium atom (Se), since its enormous and loose electron cloud, is much easier to realize orbital overlap between the adjacent PDI NFAs, afterwards enhance the charge carrier mobility (Meng et al, 2016b; Li et al., SCHEME 1 | Chemical structure and synthetic routes of FTr-3PDI-Se. 2018; Luo et al, 2018; Li G. et al, 2020; Yang et al, 2020). The FTr-3PDI-Se exhibited large conjugated planar skeleton that can effectively promote the blend films to form large aggregates, which may lead to bimolecular recombination, limiting the OSCs performance
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