Enhanced thermal stability of organic photovoltaics via incorporating triphenylamine derivatives as additives

International Conference and Exhibition on Polymer Chemistry

November 14-16, 2016 Atlanta, USA

Ying-Chieh Chao, Chia-Hsin Chuang, Hsiang-Lin Hsu, Hsing-Ju Wang, You-Chi Hsu, Chih-Ping Chen and Ru-Jong Jeng

National Taiwan University, Taiwan

Scientific Tracks Abstracts: J Material Sci Eng

Abstract :

In this work, we prepared four star-shaped conjugated small molecules, the triphenylamine dithiophene (TBT) derivatives, namely TBT-H, TBT-Br, TBT-OH and TBT-N3 presenting hydride, bromide, hydroxyl and azide terminal functional groups, respectively. These TBT derivatives were used as additives in the active layers of organic photovoltaics to investigate the effect of intermolecular interactions (TBT-H, TBT-OH) or cross-linking (TBT-N3, TBT-Br) on the long-term thermal stability of the devices. From analyses of blend film morphologies and optoelectronic and device performance, we observed significant enhancements in thermal stability during accelerated heating tests at 150�°C for the devices incorporated with the additives TBT-N3 and TBT-Br. These two additives functioned as cross-linkers and constructed local borders that effectively impeded heat-promoted fullerene aggregation, thereby leading to highly stable morphologies. When compared with corresponding normal devices, the TBT-N3-derived devices based on poly(3-hexylthiophene) exhibited greater stability with the power conversion efficiency (PCE) remaining as high as 2.5% after 144 hours at 150�°C. Because of this enhancement, a device based on an amorphous low-band gap polymer, namely poly(thieno[3,4-b] thiophene-alt-benzodithiophene) with the addition of TBT-N3 was fabricated. We observed a significant improvement in device stability, retaining approximately 60% (from 5.0 to 3.3%) of its initial PCE under accelerated heating (150�°C). In contrast, the PCE of the corresponding normal device decayed to 0.01% of its initial value.

Biography :

Ying-Chieh Chao is currently pursuing his PhD at National Taiwan University, Taipei, Taiwan. His main research focuses on organic conjugated polymers and organic photovoltaics. He has developed a cross-linking system to efficiently maintain the thermal stability of organic photovoltaics. He is also a Lecturer at Department of Materials Engineering, Ming Chi University of Technology, New Taipei City, Taiwan.

Email: d02549003@ntu.edu.tw