Synthesis and Characterization of Poly(o-anisidine-co-o-toluidine)/PCBM Composites for Optoelectronic Applications

In an organic donor-acceptor system, the efficiency is largely controlled by fundamental photophysics processes. Herein, we investigated the enhanced charge transfer (CT) behaviors between PCBM_{(2,5,10% wt)} which acts as an acceptor and poly(o-anisidine-co-o-toluidine) POA-POT which acts as a donor. The POA-POT/ PCBM nanofillers were synthesized successfully by an in-situ oxidative polymerization method. The structure and morphology of the POA-POT with and without PCBM were characterized by Fourier transformation infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM) confirming the well formation of POA-POT/PCBM_2,5,10 nanocomposites. The Uv-Vis absorption and time-resolved measurements were performed to monitor the PCBM effect on the optical properties and CT. Interestingly, the GSB kinetics in the presence of PCBM₁₀ becomes faster compared to the free copolymer (71 ps) and it fits with 32 ps time constants. This faster GSB recovery suggests efficient photoinduced ET from the free copolymer to PCBM₁₀. Direct optical band gaps of nanocomposites were calculated via Tauc’s plot method through UV-visible spectroscopy. 5% PCBM exhibits the lowest band gap compared to all the composites which is in good agreement with the electrical conductivity behavior of 5% PCBM which was studied by temperature-dependent electrical conductivity to investigate the effect of PCBM filling amount on the electrical behavior of the copolymer. Our findings confirm the fast charge transfer and the well dispersion of PCBM in the copolymer matrix which could help in optoelectronic applications with the enhancement on the optical and electrical behavior.