A near-infrared-harvesting n-type porphyrin-based acceptor for organic photovoltaics (OPVs) was developed. The n-type acceptor, PDI-PZn-PDI, was designed by connecting a zinc porphyrin (PZn) core to two perylenediimide (PDI) wings through ethyne bridges. A narrow bandgap of 1.27 eV was achieved through the extended π-conjugation and intramolecular charge transfer between the strongly electron-donating PZn core and the electron-accepting PDI wings. A bulk heterojunction (BHJ) structured photovoltaic device fabricated from PDI-PZn-PDI with PTB7-Th exhibited panchromatic photon-to-current conversion from 350 to 900 nm. A power conversion efficiency of 5.25% with a remarkably low Eloss of 0.54 eV was achieved by optimizing the nanomorphology of the BHJ films by adding pyridine and by controlling the ZnO/BHJ interfacial properties.
Bibliographical noteFunding Information:
The authors gratefully acknowledge support from the New and Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the granted financial resources from the Ministry of Trade, Industry and Energy, Republic of Korea (No. 20163030013960), the Technology Development Program to Solve Climate Changes (2016M1A2A2940912) of the National Research Foundation (NRF), Mid-Career Researcher Program (2014R1A2A1A10051083), the NRF Grant (2016R1A5A1012966, 2017R1C1B2010694) funded by NRF of Korean Government, and the Global Scholarship Program for Foreign Graduate Students at Kookmin University in Korea. Experiments at PLS-II 6D beamline were supported in part by UCRF, MSIP and POSTECH
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