Solution-Processable Organic Photovoltaic Cell Based on the Oligothiophene with Solubilizing β-alkyl Groups

Abstract

We synthesized a linear π-conjugated small molecule (β-DH5T) based on thiophene, using the palladium-catalyzed Suzuki coupling. The oligothiophene was designed to contain β-substituted solubilizing alkyl groups to facilitate solution processing. The organic photovoltaic cell based on β-DH5T:PC₇₁BM gave a power conversion efficiency of 0.46% with a short-circuit current of 4.69 mA/cm², an open-circuit voltage of 0.60 V, and a fill factor of 0.35, giving under AM 1.5G illumination (100 mW/cm²). The optical and electrochemical properties and molecular alignment of oligothiophene were investigated using UV-visible absorption spectroscopy, cyclic voltammetry, and thin-film X-ray diffraction studies.

Keywords:

• Organic photovoltaic cells
• solar cells
• oligothiophene
• small molecule
• solution-processing

Funding

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012R1A1A3005083).