Fluorinated Thieno[2',3':4,5]benzo[1,2-d][1,2,3]triazole: New Acceptor Unit To Construct Polymer Donors.

Xiu Jiang,Yang Yang,Xingguo Chen,Xiaowei Zhan,Jiacheng Wang

doi:10.1021/acsomega.8b02053

Abstract

A new acceptor unit, fluorinated thieno[2′,3′:4,5]benzo[1,2-d][1,2,3]triazole (fBTAZT), has been designed and synthesized to build two donor–acceptor (D–A) copolymers with the none/fluorinated benzodithiophene (BDT) unit, which have been applied as the electron-donating material with ITIC as an electron-accepting material to fabricate the nonfullerene polymer solar cells (PSCs). It is found that fluorination at the BTAZT unit and BDT unit exerts a significant influence on photophysical properties and photovoltaic performances of the PSCs. As a result, when the fluorine atom is introduced both into the BTAZT unit and the side-chain thiophene ring of the BDT unit, the corresponding polymer PfBTAZT-fBDT exhibits deeper highest occupied molecular orbital–lowest unoccupied molecular orbital energy level and shows stronger interchain interaction with a little broad and red-shift absorption and high charge mobilities as well as good phase-separated morphologies, thus leading to higher power conversion efficiency of 6.59% in nonfullerene PSCs compared with another polymer PfBTAZT-BDT without F atom at the BDT unit, indicating that fBTAZT can be acted as a medium strong organic acceptor to build D–A polymer donor for high efficient PSCs.

Highlights

Polymer solar cells (PSCs) as a new energy have got a lot of attention because of their great merits of being lightweight, constitute flexible, and low-cost fabrication.[1−7] Much recently, the power conversion efficiency (PCE) of PSCs has been boosted from over 10−11%8,9 up to over 13−14%10−16 in single junction solar cells with a medium or wide band gapconjugated polymer as a donor and narrow band gap n-type organic semiconductor (n-OS) as an acceptor
The results indicated that when one or more F atoms were attached to the BDT unit or TT unit, the photovoltaic performances of the polymer-based PSCs were varied greatly
As a new organic acceptor has been designed and Scheme 1 presents the synthetic process of fBTAZT unit and two polymers (PfBTAZT-BDT and PfBTAZT-fBDT)

Summary

Introduction

Polymer solar cells (PSCs) as a new energy have got a lot of attention because of their great merits of being lightweight, constitute flexible, and low-cost fabrication.[1−7] Much recently, the power conversion efficiency (PCE) of PSCs has been boosted from over 10−11%8,9 up to over 13−14%10−16 in single junction solar cells with a medium or wide band gapconjugated polymer as a donor and narrow band gap n-type organic semiconductor (n-OS) as an acceptor.

Results

Conclusion