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Effect of cyano substituent on photovoltaic properties of quinoxaline-based polymers
摘要： Three donor-acceptor type quinoxaline-based conjugated polymers, in which electron-donating indacenodithiophene (IDT) and indacenodithieno[3,2-b]thiophene (IDTT) were connected to the electron-accepting 2,3-diphenylquinoxaline (DPQ) derivatives, were synthesized using the Stille coupling reaction. To investigate the effects of the strong electron-withdrawing cyano (CN) substituent on the photovoltaic properties of polymers, it was selectively introduced in the DPQ unit on the polymer backbone. The combination of IDT and the standard DPQ produced the reference polymer IDT-Qx, while the coupling of IDT and IDTT with mono-CN substituted DPQ provided the target polymers IDT-QxCN and IDTT-QxCN, respectively. Owing to the significant contributions of the CN substituent, IDT-QxCN and IDTT-QxCN exhibited better photovoltaic performances than IDT-Qx reference. Furthermore, the presence of more planar two thieno[3,2-b] thiophenes in IDTT than the two thiophenes in IDT allowed IDTT-QxCN to display the highest power conversion efficiency (5.47%) with an open circuit voltage of 0.95 V, short-circuit current density of 15.30 mA cm?2, and fill factor of 56.95%.
关键词： Quinoxaline,Indacenodithiophene,Cyano substituent,Indacenodithieno[3,2-b]thiophene
更新于2025-09-23 15:21:01
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Elevated Photovoltaic Performance in Medium Bandgap Copolymers Composed of Indacenodi-thieno[3,2-b]thiophene and Benzothiadiazole Subunits by Modulating the ??-Bridge
摘要： Two random conjugated polymers (CPs), namely, PIDTT‐TBT and PIDTT‐TFBT, in which indacenodithieno[3,2‐b]thiophene (IDTT), 3‐octylthiophene, and benzothiadiazole (BT) were in turn utilized as electron‐donor (D), π‐bridge, and electron‐acceptor (A) units, were synthesized to comprehensively analyze the impact of reducing thiophene π‐bridge and further fluorination on photostability and photovoltaic performance. Meanwhile, the control polymer PIDTT‐DTBT with alternating structure was also prepared for comparison. The broadened and enhanced absorption, down‐shifted highest occupied molecular orbital energy level (EHOMO), more planar molecular geometry thus enhanced the aggregation in the film state, but insignificant impact on aggregation in solution and photostability were found after both reducing thiophene π‐bridge in PIDTT‐TBT and further fluorination in PIDTT‐TFBT. Consequently, PIDTT‐TBT‐based device showed 185% increased PCE of 5.84% profited by synergistically elevated VOC, JSC, and FF than those of its counterpart PIDTT‐DTBT, and this improvement was chiefly ascribed to the improved absorption, deepened EHOMO, raised μh and more balanced μh/μe, and optimized morphology of photoactive layer. However, the dropped PCE was observed after further fluorination in PIDTT‐TFBT, which was mainly restricted by undesired morphology for photoactive layer as a result of strong aggregation even if in the condition of the upshifted VOC. Our preliminary results can demonstrate that modulating the π‐bridge in polymer backbone was an effective method with the aim to enhance the performance for solar cell.
关键词： 2‐b]thiophene,random conjugated polymer,modulating π‐bridge,indacenodithieno[3,photovoltaic property
更新于2025-09-19 17:13:59
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Achieving high-performance non-halogenated nonfullerene acceptor-based organic solar cells with 13.7% efficiency <i>via</i> a synergistic strategy of an indacenodithieno[3,2- <i>b</i> ]selenophene core unit and non-halogenated thiophene-based terminal group
摘要： An outmost selenophene-functionalized electron-rich central core (indacenodithieno[3,2-b]selenophene) and a new non-halogenated A–D–A architecture non-fullerene small molecular acceptor (NF-SMA) (TSeTIC) based on indacenodithieno[3,2-b]selenophene as the central unit and thiophene-fused IC as a terminal group was designed and synthesized for high performance organic solar cells. In contrast to the similar NF-SMA (TTTIC) with an indacenodithieno[3,2-b]thiophene unit, TSeTIC exhibited a stronger and red-shifted absorption spectrum, higher highest occupied molecular orbital (HOMO) energy level, and enhanced electron mobility in neat thin films. Furthermore, a TSeTIC/PM6-based device presented higher hole/electron mobility, better phase separation features with favorable morphology, and higher charge dissociation and collection efficiency than a TTTIC/PM6-based device, resulting in remarkably improved Jsc and FF without sacrificing the Voc. Therefore, compared to the best PCE of 12.05% with an energy loss (Eloss) of 0.64 eV for the PM6/TTTIC device, the optimized PM6/TSeTIC device yields a significantly higher PCE of 13.71% with a higher FF of 75.9% and decreased Eloss of 0.60 eV. It is worth noting that the excellent PCE of 13.71% is the highest recorded for A–D–A structural NF-SMAs with thiophene-containing terminal groups for binary organic solar cells. These results demonstrate that the synergistic strategy of using an indacenodithieno[3,2-b]selenophene core unit and thiophene-containing IC end group is a promising avenue to enhance the PCE of non-halogenated NF-SMAs with high Voc and FF as well as low Eloss.
关键词： indacenodithieno[3,2-b]selenophene,non-halogenated nonfullerene acceptor,organic solar cells,synergistic strategy,thiophene-based terminal group
更新于2025-09-16 10:30:52