Synthesis and characterization conjugated oligomer based on phenothiazine derivative

ABSTRACT

An acceptor-donor-acceptor (A-D-A) type oligomer based on benzothiadiazole and phenothiazine, 3,7-bis-[5-(7-methyl-benzo[1,2,5]thiadiazol-4-yl)-thiophen-2-yl]-10-(2-octyl-dodecyl)-10H-phenothiazine (PTBT), is synthesized by the Suzuki Coupling reaction. In addition, we introduce thiophene (T) ring as a π-bridge to extend the effective conjugation length. To investigate the effect of combination between strong electron donor and strong electron withdrawing on the diverse properties of conjugated oligomer on PTBT, optical and electrochemical properties are examined using UV-Vis absorption spectra and cyclic volatommograms (CV) that revealing HOMO/LUMO level at −5.36 eV/−3.18 eV with an optical band gap of 2.18 eV, respectively. Inverted-type organic solar cells (OSCs) with a configuration of ITO/ZnO/PTBT:PC₇₁BM/MoO₃/Al are fabricated. Maximum power conversion efficiency of the organic solar cells (OSCs) based on PTBT is showed up to 0.44% with a short-circuit current density (J_sc) of – 1.63 mA/cm², V_oc of 0.87 V, and fill factor (FF) of 30.9%.

KEYWORDS:

• Benzothiadiazole
• organic solar cells
• phenotiazine
• small-molecule

Funding

This research was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (20153010140030).