New A-D-A type small molecules based on benzodithiophene derivative for organic solar cells

ABSTRACT

A synthesized of acceptor-donor-acceptor (A-D-A) type oligomer based on benzodithiophene (BDT) as a donor (D) unit and phenylisoxazol (OX) as an acceptor (A) is to investigate the effect of combination between the strong electron donor and a strong electron acceptor. In addition, we introduce hexylthiophene (HT) ring as a π-bridge to extend the effective conjugation length and increase the solubility. Here we report the performance of 2,6-(4-(thiophen-2-yl)methylene)-3-phenylisoxazol-5(4H)-one)-4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b′]dithiophene) (BDT-HTOX) employing as the electron donor in the inverted organic solar cells and PC₇₁BM as the electron acceptor unit. UV-Vis absorption and electrochemical measurements investigated the optoelectronic properties that revealing the HUMO/LUMO level at −3.72 eV/−5.44 eV with an optical band gap of 1.72 eV for BDT-HTOX. Maximum power conversion efficiency based on BDT-HTOX is showed up to 0.80% with a short-circuit current density (J_sc) of –3.26 mA/cm², V_oc of 0.88 V, and fill factor (FF) of 27.9% using chlorobenzene as a solvent for solution processed organic solar cells.

KEYWORDS:

• Benzodithiophene
• organic solar cells
• phenylisoxazol
• small-molecule

Additional information

Funding

This research work was supported by the New & Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (20153010140030) and was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (201603930154).