Novel Dimethylmethylene-Bridged Triphenylamine-PDI Acceptor for Bulk-Heterojunction Organic Solar Cells.

Yu Xiong,Zheng Zhao,Bo Wu,Ming Lin,Xiaoyan Zheng,Beng S Ong,Ping Deng,Benzhong Tang

doi:10.1002/advs.201700110

Abstract

A novel, star‐shaped electron acceptor, DMTPA‐PDI3, derived from a planar dimethylmethylene‐bridged triphenylamine core with three acetylene‐linked perylene diimide (PDI) units is developed as a nonfullerene acceptor for organic solar cells (OSCs). DMTPA‐PDI3 manifests significantly reduced intramolecular twisting, enabling sufficient system‐wide π‐electron delocalization leading to broadened spectral absorption and raised lowest unoccupied molecular orbital level. As a result, higher and more balanced hole and electron transport properties are observed. Active layers for OSCs comprising DMTPA‐PDI3 acceptor and PBT7‐Th donor exhibit suppressed intermolecular aggregation, giving rise to uniform nanophase network formation. These OSC devices have afforded respectably high power‐conversion efficiency of about 5%.

Highlights

A novel, star-shaped electron acceptor, dimethylmethene bridged triphenylamine (DMTPA)-PDI3, derived from a planar molecular orbital (LUMO) energy level, restricted optoelectronic tunability, poor dimethylmethylene-bridged triphenylamine core with three acetylene-linked morphology stability, and high costs due to perylene diimide (PDI) units is developed as a nonfullerene acceptor for organic low synthetic yields and tedious purificasolar cells (OSCs)
Our design strategy was based on the following considerations: (i) reduced twisting of PDI moieties expected as they are appositely spaced apart and that intramolecular chargetransfer (ICT) interactions between structurally conjugated PDI acceptor moieties and DMTPA donor core would encourage molecular planarization; (ii) substantial π-electronic delocalization from DMTPA donor core to PDI acceptor moieties would enhance charge transport property and broaden spectral absorption for solar energy harvesting; (iii) ICT interaction would lead to higher LUMO level, improving open-circuit voltage (Voc); and (iv) dimethyl substituents would increase molecular solubility and hamper excessive intermolecular aggregation from steric interference
Is comparable to many Bulk heterojunction (BHJ)-OSCs with PDI-based acceptors.[23,32,33,34,35,36,37]. These results have clearly demonstrated the greater utility of planar DMTPA as a core structure for designing efficient electron acceptors as fullerene replacement for OSCs

Summary

Introduction

A novel, star-shaped electron acceptor, DMTPA-PDI3, derived from a planar molecular orbital (LUMO) energy level, restricted optoelectronic tunability, poor dimethylmethylene-bridged triphenylamine core with three acetylene-linked morphology stability, and high costs due to perylene diimide (PDI) units is developed as a nonfullerene acceptor for organic low synthetic yields and tedious purificasolar cells (OSCs). Our design strategy was based on the following considerations: (i) reduced twisting of PDI moieties expected as they are appositely spaced apart and that intramolecular chargetransfer (ICT) interactions between structurally conjugated PDI acceptor moieties and DMTPA donor core would encourage molecular planarization; (ii) substantial π-electronic delocalization from DMTPA donor core to PDI acceptor moieties would enhance charge transport property and broaden spectral absorption for solar energy harvesting; (iii) ICT interaction would lead to higher LUMO level, improving open-circuit voltage (Voc); and (iv) dimethyl substituents would increase molecular solubility and hamper excessive intermolecular aggregation from steric interference.

Results

Conclusion