Dithienobenzothiadiazole-Based Conjugated Polymer: Processing Solvent-Relied Interchain Aggregation and Device Performances in Field-Effect Transistors and Polymer Solar Cells

• Published in: Macromolecular rapid communications. Vol. 35; no. 22; pp. 1960 - 1967
• Main Authors: Huang, Jun, Zhu, Yongxiang, Chen, Junwu, Zhang, Lianjie, Peng, Junbiao, Cao, Yong
• Format: Journal Article
• Language: English
• Published: Weinheim Blackwell Publishing Ltd 01.11.2014; Wiley; Wiley Subscription Services, Inc
• Subjects: Agglomeration; Applied sciences; D-A conjugated copolymers; Devices; dithienobenzothiadiazoles; Electric Power Supplies; Electrochemical Techniques; Electronics; Energy; Energy conversion efficiency; Exact sciences and technology; Hole mobility; Molecular Structure; Natural energy; organic field-effect transistors; Organic polymers; Photovoltaic cells; Photovoltaic conversion; Physicochemistry of polymers; polymer solar cells; Polymers - chemical synthesis; Polymers - chemistry; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts; salvation ability; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Solar cells; Solar cells. Photoelectrochemical cells; Solar Energy; Solvation; Solvents - chemistry; Temperature; Thiadiazoles - chemistry; Thiophenes - chemistry; Transistors; Transistors, Electronic; Solvent effect; Terpolymer; polymer solar cells; Organic solar cells; Fabrication property relation; Fill factor; Thermal stability; salvation ability; organic field-effect transistors; Optical properties; Nitrogen heterocycle copolymer; Size effect; Aromatic copolymer; Thiophene derivative copolymer; Optical absorption; Stille coupling; Short circuit currents; Solution polycondensation; Hole mobility; Active layer; Thiophene copolymer; Experimental study; Open circuit voltage; Field effect transistor; D-A conjugated copolymers; Electrochemical properties; Conjugated copolymer; Preparation; dithienobenzothiadiazoles
• ISSN: 1022-1336; 1521-3927
• DOI: 10.1002/marc.201400461

DTfBT‐Th3, a new conjugated polymer based on dithienobenzothiadiazole and terthiophene, possesses a bandgap of ≈1.86 eV and a HOMO level of −5.27 eV. Due to strong interchain aggregation, DTfBT‐Th3 can not be well dissolved in chloro­benzene (CB) and o‐dichlorobenzene (DCB) at room temperature (RT), but the polymer can be processed from hot CB and DCB solutions of ≈100 °C. In CB, with a lower solvation ability, a certain polymer chain aggregation can be preserved, even in hot solution. DTfBT‐Th3 displays a field‐effect hole mobility of 0.55 cm2 V−1 s−1 when fabricated from hot CB solution, which is higher than that of the device processed from hot DCB (0.16 cm2 V−1 s−1). In DTfBT‐Th3‐based polymer solar cells, a good power conversion efficiency from 5.37% to 6.67% can be achieved with 150−300 nm thick active layers casted from hot CB solution, while the highest efficiency for hot DCB‐processed solar cells is only 5.07%. The results demonstrate that using a solvent with a lower solvation ability, as a “wet control” process, is beneficial to preserve strong interchain aggregation of a conjugated polymer during solution processing, showing great potential to improve its performances in optoelectronic devices. Due to strong interchain aggregation, DTfBT‐Th3, a new conjugated polymer based on dithienobenzothiadiazole and terthiophene (Eg = 1.86 eV and HOMO = −5.27 eV), can only be processed with hot chlorobenzene (CB) and o‐dichlorobenzene (DCB) solutions of ≈100 °C. In CB having a lower solvation ability, polymer chain aggregation can be even preserved in hot solution, and DTfBT‐Th3‐based devices with a higher hole mobility of 0.55 cm2 V−1 s−1 and a power conversion efficiency up to 6.67% are obtained.