10.20% Efficiency polymer solar cells via employing bilaterally hole-cascade diazaphenanthrobisthiadiazole polymer donors and electron-cascade indene-C70 bisadduct acceptor. (July 2016)

• Record Type: Journal Article
• Authors: Xu, Xiaopeng; Li, Zuojia; Wang, Zhenguo; Li, Kai; Feng, Kui; Peng, Qiang
• Is Part Of: Nano energy. Volume 25(2016:Jul.)
• Page Start: 170
• Page End: 183
• Publication Date: 2016-07
• Subjects: Polymer solar cells -- Low-lying HOMO energy levels -- Cascade energy band structures -- Ternary blend solar cells -- Quaternary blend solar cells; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2016.04.048
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: A series of crystalline copolymers, PBDTSA-DAPT, PBDTTA-DAPT and PBDTTS-DAPT, have been designed towards the application of multi-blend polymer solar cells (PSCs). These copolymers exhibit low-lying HOMO levels by incorporating benzodithiophene (BDT) donor and 9, 10-diazaphenanthro[3, 4- c ;5, 6- c ]bis[1, 2, 5]thiadiazole (DAPT) acceptor in the main chains. They were added as the hole-cascade polymer donors into the PTB7: PC71 BM blend. When adding 10 wt% of the resulting copolymers, the PCEs of 8.59%, 9.03% and 8.91% were achieved for PBDTSA-DAPT-, PBDTTA-DAPT- and PBDTTS-DAPT-based ternary devices, respectively. In order to further elevate the performance of PBDTTA-DAPT devices, indene-C70 bisadduct (IC70 BA) was also incorporated into the PBDTTA-DAPT-based ternary blend. This cascade band structure would give steadier energy level alignment and afford more charge transfer channels, which could promote simultaneously both the hole and electron transfer. When adding 5 wt% of IC70 BA, the quaternary PSC device showed a top PCE of 10.20%. This PCE value is the best efficiency for PTB7 based PSCs reported so far. Our work not only demonstrates a design strategy for high performance hole-cascade polymer donors in multi-blend PSCs, but also provides a first quaternary strategy with bilateral cascade energy band structures to increase the V oc, J sc and FF simultaneously for high efficient organic solar cell applications. Graphical abstract: A series of new crystalline copolymers, PBDTSA-DAPT, PBDTTA-DAPT and PBDTTS-DAPT, were synthesized towards multi-blend polymer solar cells. When adding 10% of PBDTTA-DAPT, a high PCE of 9.03% was achieved from its ternary devices. Above optimized ternary blend was incorporated with IC70 BA acceptor as an electron-cascade material to form a quaternary blend with D1: D2: A1: A2 configuration. Thus, when adding 5% percentage of IC70 BA, the quaternary device showed a high PCE of 10.20%. Highlights: New crystalline DAPT copolymers were developed as the efficiently hole-cascaded polymer donors. Efficient ternary and quaternary solar cells with 10.20% PCE were fabricated. Bilaterally hole-cascade and electron-cascade alignments were first introduced simultaneously to enhance the photovoltaic performance.