Tailorable PC₇₁BM Isomers: Using the Most Prevalent Electron Acceptor to Obtain High‐Performance Polymer Solar Cells

Abstract

Despite being widely used as electron acceptor in polymer solar cells, commercially available PC BM (phenyl-C -butyric acid methyl ester) usually has a "random" composition of mixed regioisomers or stereoisomers. Here PC BM has been isolated into three typical isomers, α-, β - and β -PC BM, to establish the isomer-dependent photovoltaic performance on changing the ternary composition of α-, β - and β -PC BM. Mixing the isomers in a ratio of α/β /β =8:1:1 resulted in the best power conversion efficiency (PCE) of 7.67 % for the polymer solar cells with PTB7:PC BM as photoactive layer (PTB7=poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]]). The three typical PC BM isomers, even though sharing similar LUMO energy levels and light absorption, render starkly different photovoltaic performances with average-performing PCE of 1.28-7.44 % due to diverse self-aggregation of individual or mixed PC BM isomers in the otherwise same polymer solar cells.

Tailoring Functional Terminals on Solution-Processable Fullerene Electron Transporting Materials for High Performance Perovskite Solar Cells

“…To investigate the potential of three synthesized fulleropyrrolidine derivatives as ETMs for PSCs, UV-Vis absorption, and CV characterizations were performed to determine their optical and electrochemical properties, as shown in Figures S12–S14 , Figure 1 b, and Table S1 [ 33 ]. Obviously, all compounds showed completely reversible CV signals.…”

Beyond Metal Oxides: Introducing Low‐Temperature Solution‐Processed Ultrathin Layered Double Hydroxide Nanosheets into Polymer Solar Cells Toward Improved Electron Transport

“…Materials : The indium tin oxide (ITO) glass substrate with a sheet resistance of 10 Ω □ −1 was purchased from Shenzhen Nan Bo Group, China. All chemicals were used as received without further purification, including zinc acetate dehydrate (C 4 H 6 O 4 Zn · 2H 2 O, 99%, Alfa), 2‐methoxyethanol (HOCH 2 CH 2 OCH 3 , 99%, Alfa), ethanolamine (HOCH 2 CH 2 NH 2 , 98%, Alfa), magnesium nitrate hexahydrate (Mg(NO 3 ) 2 · 6H 2 O, 99%, Alfa), aluminum nitrate nonahydrate (Al(NO 3 ) 3 · 9H 2 O, 99%, Acros), PBDTTT‐C (Solarmer Material Inc.), PTB7‐Th (One‐Material), PC 71 BM (99.9%, Solenne BV., as a mixture of several isomers), molybdenum trioxide (MoO 3 , 99.9995%, Alfa), lead iodide (PbI 2 , 99.999%, TCI), methylammonium iodide (MAI, Xi'an Polymer Light Technology Corp), spiro‐OMeTAD (One‐Material), Li‐bis(trifluoromethanesulfonyl) imide (Li‐TFSI, Sigma). The solvents, including chlorobenzene, o ‐dichlorobenzene, dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), were purchased from Sigma–Aldrich.…”

Isomer‐Dependent Photovoltaic Properties of the [6,6]‐Phenyl‐C61 (or C71)‐Butyric Acid Methyl Esters

“…Almost at the same time, our group isolated the PC 71 BM mixture into α‐, β 1 ‐, and β 2 ‐PC 71 BM isomers, which was the first report about the separation of β‐PC 71 BM isomers. [ 26 ] The LUMO energy levels of α‐, β 1 ‐, and β 2 ‐PC 71 BM were −3.74, −3.73, and −3.72 eV, respectively, which suggests less adverse effect of energetic disorder on photovoltaic performance. In addition, their optical properties were similar to each other.…”

“…Previously, we demonstrated the feasibility of fullerene formulation based on blending three PC 71 BM isomers to improve the performance of PTB7: PC 71 BM‐based solar cells. [ 26 ] Subsequently, we further investigated the effect of PC 71 BM isomer formulation on device performance of P3HT: PC 71 BM solar cells to demonstrate the generality of fullerene formulation with different donors. [ 33 ] The PCEs of P3HT: PC 71 BM devices varied from 0.87% to 4.01% by changing the PC 71 BM isomer formulation.…”