Propeller-Like All-Fused Perylene Diimide Based Electron Acceptors With Chalcogen Linkage for Efficient Polymer Solar Cells.

Ying Li,Yufei Gong,Qiang Peng,Xiaopeng Xu,Liyang Yu,Yongjie Che

doi:10.3389/fchem.2020.00350

Abstract

Perylene diimide (PDI) is a widely explored chromophore for constructing non-fullerene acceptors (NFAs) for polymer solar cells (PSCs). The advantage of using PDI derivatives lies in the readily availability of PDI unit which largely reduces the synthesis cost and improves material stability. Indeed, the recent development of high performance NFAs shed light on the feasibility of the commercialization, but the complex synthesis and poor stability of the top performing NFAs cast a shadow on this bright future. Our previous work has demonstrated a propeller-like structure with three PDIs lined to a benzene center core with a C-C bond which prevented the PDIs to aggregate into undesired large crystals. In this work, we designed and synthesized three new propeller-like PDI derivatives with extra chalcogen linkages between the PDIs and the center core to form all-fused rigid structures. These molecules showed more suitable absorption range than that of their unfused counterparts when blend with donor polymer PTB7-Th. Comparing between the molecules with extra oxygen, sulfur or selenium linkages, the sulfur-based BTT-PDI outperformed the others due to its higher photon absorption and charge transport abilities. This work demonstrated the great potential of PDI derivatives for PSC applications and explored the influences of linkage type on the fused PDI derivatives, which provided a useful tuning knob for molecular design of PDI-based NFAs in the future.

Highlights

Polymer solar cell (PSC) is widely considered as a viable alternative for solar energy harvesting for its relatively low manufacturing cost and intrinsic characteristics such as light weight and flexibility (Inganäs, 2018)
Thermal stabilities of the three non-fullerene acceptors (NFAs) were examined by thermogravimetry analysis (TGA, Figure 1A)
Differential scanning calorimetry (DSC, Figure 1B) scans of the three NFAs were performed to look for thermal transitions

Summary

INTRODUCTION

Polymer solar cell (PSC) is widely considered as a viable alternative for solar energy harvesting for its relatively low manufacturing cost and intrinsic characteristics such as light weight and flexibility (Inganäs, 2018). A propeller-like structure connecting three or four PDI molecules with a center core through a flexible linkage have been demonstrated with success (Lin et al, 2014, 2016; Lee et al, 2016; Duan et al, 2017b; Sun et al, 2017; Bian et al, 2019; Tang et al, 2019; Weng et al, 2019; Zhang et al, 2019; Ding et al, 2020; Wang et al, 2020). We elegantly separated the three PDIs of the TPH with an additional planar five-membered heterocyclic ring between the PDIs and the benzene ring at the center This design was in hope to further extend the conjugation length and reduce the molecule torsion. The highest performances were observed with BTT-PDI for its high photon absorption and charge transport mobility

RESULTS AND DISCUSSIONS

CONCLUSIONS

DATA AVAILABILITY STATEMENT