High‐Performance Polymer Solar Cells Based on a Wide‐Bandgap Polymer Containing Pyrrolo[3,4‐f]benzotriazole‐5,7‐dione with a Power Conversion Efficiency of 8.63%

Abstract

A novel donor–acceptor type conjugated polymer based on a building block of 4,8‐di(thien‐2‐yl)‐6‐octyl‐2‐octyl‐5H‐pyrrolo[3,4‐f]benzotriazole‐5,7(6H)‐dione (TZBI) as the acceptor unit and 4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)­benzo­[1,2‐b:4,5‐b′]dithiophene as the donor unit, named as PTZBIBDT, is developed and used as an electron‐donating material in bulk‐heterojunction polymer solar cells. The resulting copolymer exhibits a wide bandgap of 1.81 eV along with relatively deep highest occupied molecular orbital energy level of −5.34 eV. Based on the optimized processing conditions, including thermal annealing, and the use of a water/alcohol cathode interlayer, the single‐junction polymer solar cell based on PTZBIBDT:PC71BM ([6,6]‐phenyl‐C71‐butyric acid methyl ester) blend film affords a power conversion efficiency of 8.63% with an open‐circuit voltage of 0.87 V, a short circuit current of 13.50 mA cm−2, and a fill factor of 73.95%, which is among the highest values reported for wide‐bandgap polymers‐based single‐junction organic solar cells. The morphology studies on the PTZBIBDT:PC71BM blend film indicate that a fibrillar network can be formed and the extent of phase separation can be mani­pulated by thermal annealing. These results indicate that the TZBI unit is a very promising building block for the synthesis of wide‐bandgap polymers for high‐performance single‐junction and tandem (or multijunction) organic solar cells.

Imide‐Functionalized Polymer Semiconductors

“…Chem.E ur.J. 2019,25,[87][88][89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104][105] www.chemeurj.org which enabled the polymers with n-type characteristics in OTFTs. OTFT devicesb ased on polymers 75 and 77 using trimethoxyoctadecylsilane as the self-assembled monolayer showedn -type transport characteristics with am aximum m e,OTFT of 0.11a nd 0.4 cm 2 V À1 s À1 ,r espectively,w hereasp olymer 76 exhibited ambipolar characterw ith an average m e,OTFT /m h,OTFT value of 0.13/0.011cm 2 V À1 s À1 owing to the elevatedH OMO for more facile hole injection.…”

“…Eur.J. 2019,25,[87][88][89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104][105] www.chemeurj.org PCE of 8.61 %w as achieved with a V oc of 0.84 V, J sc of 14.26 mA cm À2 ,a nd FF of 71 %. [67] To increase the J sc of all-PSCs, the same group synthesized as eries of fluorine-containing NDI-thiophene-NDI-bithiophene based regio-random terpolymers 54 to increase the dielectric constant of the polymer:polymer blend for the purpose of reducing the binding energy of excitons.…”

Recent Progress in All‐Polymer Solar Cells Based on Wide‐Bandgap p‐Type Polymers

“…The TzBI structure‐unit was initially designed as a weak electron‐withdrawing unit to construct WBG p ‐type conjugated polymers . These TzBI‐polymers (for example, PTzBI, PTzBI‐Si, etc.)…”

“…The TzBI structure-unit was initially designeda saweak electron-withdrawing unit to construct WBG p-type conjugated polymers. [50] These TzBI-polymers (for example, PTzBI, PTzBI-Si, etc.) can be used as efficient electron-donating materialsi n fullerene, non-fullerene, and all-polymer devices.…”

Efficient Non‐Fullerene Organic Solar Cells Based on a Wide‐Bandgap Polymer Donor Containing an Alkylthiophenyl‐Substituted Benzodithiophene Moiety

“…[21] To improve photovoltaic performance of ITIC-based OSCs, much effort has been devoted to developing highperformance wide-bandgap (WBG) polymer donors. [25][26][27] Recent studies indicates that by replacing the alkoxyl substitutions with alkylthio substitutions, the resulted BDT derivatives lead to obviously enhanced fill factor (FF) and PCE, which can be attributable to the enhanced crystallinity and intermolecular stacking as a result of strong S-S interactions. These WBG copolymers typically contain benzo[1,2-b : 4,5-b']dithiophene (BDT) derivatives as the donor units, and the electron-deficient 1,3-bis(thiophene-2-yl)-benzo[1,2-c : 4,5-c']dithiophene-4,8-dione, 4,8-di(thien-2-yl)-6-octyl-2-octyl-5H-pyrrolo[3,4-f]benzotriazole-5,7(6H)-dione moieties (TzBI), or 5,6-difluorobenzo[d]- [1,2,3] triazole (FTZ) as the electron-accepting units.…”