Electron Acceptors With a Truxene Core and Perylene Diimide Branches for Organic Solar Cells: The Effect of Ring-Fusion

Abstract

In this work, a star-shaped planar acceptor named FTr-3PDI was synthesized via ring-fusion between truxene core and three bay-linked perylene diimide (PDI) branches. Compared to the unfused non-planar acceptor Tr-3PDI, FTr-3PDI exhibits better structural rigidity and planarity, as well as more effective conjugation between truxene core and PDI branches. As a result, FTr-3PDI shows up-shifted energy levels, enhanced light absorption coefficient, increased electron mobility, and more favorable phase separation morphology in bulk-heterojunction (BHJ) blend films as compared to Tr-3PDI. Consequently, FTr-3PDI afforded higher power conversion efficiency (PCE) in BHJ solar cells when blended with a polymer donor PTB7-Th. This work demonstrates that ring-fusion is a promising molecular design strategy to combine the merits of truxene and PDI for non-fullerene acceptors used in organic solar cells.

Push-Pull Zinc Porphyrins as Light-Harvesters for Efficient Dye-Sensitized Solar Cells

“…For example, some electron-donating groups in organic sensitizer were successfully applied in porphyrin, such as N-annulated perylene ( 26 in Figure 4 ) (Jiao et al, 2011 ; Luo et al, 2013 , 2016 ), 2-diphenylaminothiophene ( 23 in Figure 4 ) (Wang et al, 2014d ), indoline ( 24 in Figure 4 ) (Pellej et al, 2014 ), phenothiazine ( 31 in Figure 4 ) (Xie et al, 2015 ), and even ferrocene (van der Salm et al, 2015 ). Some concepts from low-band-gap polymer were successfully applied in adjusting the absorption area and energy alignment of the porphyrins, such as weak donor-strong acceptor (Zhou et al, 2012 ; Bai et al, 2018 ; Lin et al, 2018 ; Xie et al, 2018 ), which will be discussed in the following part.…”

Truxene Functionalized Star-Shaped Non-fullerene Acceptor With Selenium-Annulated Perylene Diimides for Efficient Organic Solar Cells

“…However, the single bonding connection between central core and PDIs would weaken charge mobility due to an excessive twist geometry, giving a low OSCs performance. Therefore, the proper twisted non-planar structures, i.e., good balance of desirable film morphology with proper domain size and sufficient charge transport ability seems to be the key point for developing highperformance PDI electron acceptors (Lin et al, 2018a). Interestingly, 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 (Hartnett et al, 2016;Meng et al, 2016aMeng et al, , 2017Zhong et al, 2016;Wang et al, 2017;Lin et al, 2018a;Chen et al, 2020).…”

“…The researcher verified that changing the planarity of the PDIs is the popular methods to avoid this strong aggregation (Zhong et al, 2014 , 2016 ; Lin et al, 2016 ; Zhang et al, 2016 ; Duan et al, 2017a ; Liu X. et al, 2017 ; Liu et al, 2018 ). For example, various 3D electron acceptors with the central aromatic core (atom) and twisted PDI trimers or tetramer were investigated (Liu Y. H. et al, 2015 ; Lee et al, 2016 ; Zhan et al, 2017 ; Zhang A. D. et al, 2017 ; Lin et al, 2018a ; Liu W. X. et al, 2020 ). A twisted configuration of PDIs is confirmed effectively to avoid large aggregation.…”

“…However, the single bonding connection between central core and PDIs would weaken charge mobility due to an excessive twist geometry, giving a low OSCs performance. Therefore, the proper twisted non-planar structures, i.e., good balance of desirable film morphology with proper domain size and sufficient charge transport ability seems to be the key point for developing high-performance PDI electron acceptors (Lin et al, 2018a ).…”

Diels–Alder Cycloaddition to the Bay Region of Perylene and Its Derivatives as an Attractive Strategy for PAH Core Expansion: Theoretical and Practical Aspects

“…Perylene derivatives are also essential components of hybrid inorganic/organic material systems, which are often more attractive than “pure” inorganic or organic materials [ 47 , 48 ]. Perylene imides (PIs) and bisimides (PBIs) are the most frequently researched because of their attractive properties; i.e., they are outstandingly multifaceted organic chromophores, which makes them extremely useful materials in the field of organic electronics [ 16 , 18 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 ], organic photovoltaics [ 63 , 64 , 65 , 66 , 67 , 68 ], and photonics [ 69 , 70 , 71 , 72 ]. Among the advantages of PIs and PBIs are their low-cost and commercially available starting material, rigid and planar aromatic scaffolds, extraordinary thermal and photochemical stability, appreciable and tunable visible light absorption, unique self-assembly behaviors [ 59 , 73 , 74 , 75 , 76 ], and low-lying FMO (frontier molecular orbitals) [ 59 , 76 , 77 ].…”