Mixed-flow design for microfluidic printing of two-component polymer semiconductor systems

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 117; no. 30; pp. 17551 - 17557
• Main Authors: Wang, Gang, Feng, Liang-Wen, Huang, Wei, Mukherjee, Subhrangsu, Chen, Yao, Shen, Dengke, Wang, Binghao, Strzalka, Joseph, Zheng, Ding, Melkonyan, Ferdinand S., Yan, Jinhui, Stoddart, J. Fraser, Fabiano, Simone, DeLongchamp, Dean M., Zhu, Meifang, Facchetti, Antonio, Marks, Tobin J.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 28.07.2020
• Subjects: Atomic force microscopy; Benzotriazole; Blade coating; Circuits; Conformation; Design; Dicarboximide; Energy conversion efficiency; ENGINEERING; Flow simulation; Fluid dynamics; Fluid flow; Heterojunctions; Laminar flow; Microfluidics; Microscopy; Mixed-flow design; Naphthalene; Optoelectronics; Phase purity; Photovoltaic cells; Photovoltaics; Physical Sciences; Polymers; Polystyrene; Polystyrene resins; Printed electronics; Printing; Purity; Semiconducting polymer; Semiconductor devices; Short circuit currents; Short-circuit current; Soft x rays; Solar cells; Thin film transistors; Thin films; Transistors; Transmission electron microscopy; Two-component; X-ray scattering; mixed-flow design; semiconducting polymer; two component; phase purity; printed electronics
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.2000398117

The rational creation of two-component conjugated polymer systems with high levels of phase purity in each component is challenging but crucial for realizing printed soft-matter electronics. Here, we report a mixed-flow microfluidic printing (MFMP) approach for two-component π-polymer systems that significantly elevates phase purity in bulk-heterojunction solar cells and thinfilm transistors. MFMP integrates laminar and extensional flows using a specially microstructured shear blade, designed with fluid flow simulation tools to tune the flow patterns and induce shear, stretch, and pushout effects. This optimizes polymer conformation and semi-conducting blend order as assessed by atomic force microscopy (AFM), transmission electron microscopy (TEM), grazing incidence wide-angle X-ray scattering (GIWAXS), resonant soft X-ray scattering (R-SoXS), photovoltaic response, and field effect mobility. For printed all-polymer (poly[(5,6-difluoro-2-octyl-2H-benzotriazole-4,7-diyl)-2,5-thiophenediyl[ 4,8-bis[5-(2-hexyldecyl)-2-thienyl]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl]-2,5-thiophenediyl]) [J51]:(poly{[N,N′-bis(2-octyldodecyl) naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)}) [N2200]) solar cells, this approach enhances short-circuit currents and fill factors,with power conversion efficiency increasing from 5.20% for conventional blade coating to 7.80% for MFMP. Moreover, the performance of mixed polymer ambipolar [poly(3-hexylthiophene-2,5-diyl) (P3HT):N2200] and semiconducting:insulating polymer unipolar (N2200:polystyrene) transistors is similarly enhanced, underscoring versatility for two-component π-polymer systems. Mixed-flow designs offer modalities for achieving high-performance organic optoelectronics via innovative printing methodologies.