Energetic Disorder and Activation Energy in Efficient Ternary Organic Solar Cells with Nonfullerene Acceptor Eh‐IDTBR as the Third Component

Abstract

Solution‐processed ternary organic solar cells (OSCs) contain a third component in the active layer in addition to the donor/acceptor materials. Two main avenues are considered to fabricate ternary OSCs: 1) to improve the short‐circuit current density by the selected third component that broadens and/or enhances the absorption of the host films and 2) to increase the fill factor by adding materials with diverse crystallinity to tune the film morphology. However, little work is reported for the improvement of open‐circuit voltage (VOC), energetic disorder, charge transfer state energy (ECT), and activation energy in ternary OSCs. Herein, ternary OSCs with active layer composed of PCE10:F8IC:Eh‐IDTBR as the model to examine these parameters in addition to the morphology are used. In the ternary device, the additional Eh‐IDTBR improves the crystallinity of the acceptor phase in the ternary mixture; the VOC is 58 mV higher than that of the reference caused by the reduced energetic disorder; due to the good miscibility of Eh‐IDTBR with both PCE10 and F8IC, only 50 meV in ECT is observed; and the zero‐field activation energy is lower than that for the reference. The findings provide an alternative way to understand the complex ternary OSC structural–electrical properties’ correlations.

Elevated Photovoltaic Performance in Medium Bandgap Copolymers Composed of Indacenodi-thieno[3,2-b]thiophene and Benzothiadiazole Subunits by Modulating the π-Bridge

“…Bistin 2,8-bis(trimethyltin)-6,6,12,12-tetra(4hexylphenyl)-indacenodithieno [3,2-b]thiophene (IDTTSn) was prepared according to our reported method [34]. Symmetric dibromide 4,7-bis(5-bromo-4-octylthien-2-yl)benzo[c] [1,2,5]thiadiazole (DTBTBr 2 ) and unsymmetric 4-bromo-7-(5-bromo-4-octylthien-2-yl)benzo[c] [1,2,5]thiadiazole (TBTBr 2 ), as well as fluorinated 4-bromo-7-(5-bromo-4-octylthien-2-yl)-5,6-difluorobenzo[c] [1,2,5]thiadiazole (TFBTBr 2 ) were synthesized and described in Supporting Information.…”

“…The black solid was collected and completely dried under vacuum overnight to obtain the target material with a yield of 92~98%. [6,6,12,12- [6,6,12,12-tetra(4-hexylphenyl)indacenodithieno [3,2-b]thiophene-2,8-diyl-co-7-(4-octylthien-2-yl)benzo[c] [1,2,5]thiadiazole-4,5 -diyl] (PIDTT-TBT) IDTTSn (128.0 mg, 0.095 mmol) and TBTBr 2 (46.46 mg, 0.095 mmol). The random polymer PIDTT-TBT was collected as black solid possessing metallic luster (118.9 mg, yield: 93.0%).…”

“…By virtue of the intriguing features of environmentally friendly, inexhaustibility, and widespread distribution, solar energy as one kind of green renewable energy has yielded more and more attention [1,2]. Among the multitudinous solar energy utilization technologies, bulk-heterojunction (BHJ) polymer solar cells (PSCs) whose photoactive layer consists of p-type π-conjugated polymers that 185% increased PCE from 2.05 to 5.84% was achieved when reducing the thiophene π-bridge in PIDTT-TBT.…”

“…By inserting the flanked thiophene bridge on the two sides of thiadiazole[3,4-c]pyridine (PyT) or dibenzothiophene-S,S-dioxide units, the elevated E HOMO s never evidently down-shifted the V OC and thus the increased PCE were achieved due to an improved Polymers 2020, 12, 368 3 of 22 FF [38,67]. For naohtho [1,2-c:5,6-c ]bis [1,2,3]triazole (TZNT) system, the adding of thiophene bridge enabled the red-shifted absorption and in turn a slightly increased J SC , however the rising E HOMO severely limited the V OC , leading to a deteriorated PCE [58]. Extending the π-bridge from thiophene to TT, multiple investigation systems consisting of benzothiadiazole (BT) [51], difluoro-substituted-BT [43], dialkyloxy-substituted BT [54,64], thieno[3,4-c]pyrrole-4,6-dione (TPD) [56], thiazolo[5,4-d]thiazole (TzTz) [62] and so on were systematically investigated and the optimized PCEs were achieved.…”

Fluorination Effect for Highly Conjugated Alternating Copolymers Involving Thienylenevinylene-Thiophene-Flanked Benzodithiophene and Benzothiadiazole Subunits in Photovoltaic Application

“…Of all the third generation solar cell technologies (i.e., organic solar cells, perovskite solar cells, and dye-sensitized solar cells, and so on), bulk-heterojunction (BHJ) polymer solar cells (PSCs) have attracted broad academic and industrial interests, because of attractive features including flexibility, lightweight, large area, low-cost production, and environmental friendliness [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The photovoltaic performance of BHJ PSCs was highly dependent on the semiconductor materials used as the photoactive layer.…”