SYNTHESIS AND STUDIES OF LONG-WAVELENGTH ABSORBING ORGANIC SEMICONDUCTORS FOR OPTOELECTRONICS

Owing to the unique ability of organic semiconductors exhibiting absorption in long-wavelength regions of visible spectrum to capture low-energy photons, they play a crucial role in advancement of next-generation optoelectronic devices such as high-efficiency solar cells, photodetectors, biomedical imaging, and optical communication devices.1Additionally, such materials are suitable for night vision in security and surveillance which helps to improve sensitivity towards low light conditions. Carbazole moiety is frequently used as an electron-donating group in the design of π-conjugated molecules owing to the hole-transporting capabilities, optical properties, thermal and chemical stability, and easy structural modification of carbazole derivatives. 2 Also, the strong electron acceptors, 1,1,2,2-tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) are highly reactive toward electron-rich alkynes.2,3 Taking into account, the increased demand for the development of organic semiconductors exhibiting absorption in long-wavelength regions of the visible spectrum, we designed novel materials containing 9-ethyl carbazole as donor unit appended with strong acceptor units i.e. TCNQ and TCNE. The synthesis of the designed compounds was successfully furnished using two step synthetic schemes followed by structural characterization using NMR and mass spectrometry. The photophysical, electrochemical and theoretical analysis of the synthesized compounds was carried out and the structure-property relationship was established. Conclusively, the newly synthesized materials can be suitable for photonic and optical devices particularly for organic photodetectors. This project has received funding from the Research Council of Lithuania (LMTLT), agreement No S-MIP-22-78.