Two Well‐Miscible Acceptors Work as One for Efficient Fullerene‐Free Organic Solar Cells

Abstract

High-performance ternary organic solar cells are fabricated by using a wide-bandgap polymer donor (bithienyl-benzodithiophene-alt-fluorobenzotriazole copolymer, J52) and two well-miscible nonfullerene acceptors, methyl-modified nonfullerene acceptor (IT-M) and 2,2'-((2Z,2'Z)-((5,5'-(4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydros-indaceno[1,2-b:5,6-b']dithiophene-2,7-diyl)bis(4-((2-ethylhexyl)oxy)thiophene-5,2-diyl))bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (IEICO). The two acceptors with complementary absorption spectra and similar lowest unoccupied molecular orbital levels show excellent compatibility in the blend due to their very similar chemical structures. Consequently, the obtained ternary organic solar cells (OSC) exhibits a high efficiency of 11.1%, with an enhanced short-circuit current density of 19.7 mA cm and a fill factor of 0.668. In this ternary system, broadened absorption, similar output voltages, and compatible morphology are achieved simultaneously, demonstrating a promising strategy to further improve the performance of ternary OSCs.

Miscibility Tuning for Optimizing Phase Separation and Vertical Distribution toward Highly Efficient Organic Solar Cells

“…[25] Although both ternary OSCs and tandem OSCs could improve the power conversion efficiency (PCE) value to about 15%, the ternary strategy possessing simplicity of processing active layer exhibits great potential in R2R technology. [29] Especially, many researchers have realized the importance of miscibility in ternary OSCs, [28,[35][36][37] such as the appearance of Förster resonance energy transfer, [38] distribution of third additive on the interfaces of donor and acceptor, [39] formation of alloy with donor or acceptor, [36,37,40] etc. [6,[32][33][34] Unfortunately, most of the research work about how to select appropriate third additive is based on the trial and error strategy, which is a process of labor and time consumption.…”

Morphology Control Enables Efficient Ternary Organic Solar Cells

“…[4,5] Consequently, much effort has been devoted to the study of NFA-based ternary OSCs. [46][47][48][49][50][51][52] Ternary organic solar cells are promising alternatives to the binary counterpart due to their potential in achieving high performance. [39][40][41][42][43][44][45] In terms of ternary blend incorporating two NFAs, impressive progresses have been also obtained.…”

“…[21,22] Different ternary blends containing one NFA paired with two donors or one donor/one fullerene derivative exhibited high PCEs over 12%. [46][47][48][49][50][51][52] Ternary organic solar cells are promising alternatives to the binary counterpart due to their potential in achieving high performance. [46][47][48][49][50][51][52] Ternary organic solar cells are promising alternatives to the binary counterpart due to their potential in achieving high performance.…”

Design and synthesis of low band gap non-fullerene acceptors for organic solar cells with impressively high Jsc over 21 mA cm_2

“…could be tuned through the delicate chemical structure design [17,18]. For example, 4,9-dihydro-s-indaceno [ [10,18] were used as the central building blocks to construct the A-D-A NFAs such as ITIC [10], ITIC-Th [22] and IT-M [21,23], etc. with 3-(dicyanomethylidene)-indan-1-one and its derivatives as the end groups, and PCE over 11% have been achieved.…”

“…To this end, the strategy of using wide bangap donor materials and low bandgap acceptor materials to blend as the active layers has been proved to be an efficient way [21,24]. Recently, the low band gap NFAs such as IEICO [24], IT-4F [16], INIC3 [25], etc.…”