Description
Spectroscopic investigation of thiophene-diketopyrrolopyrrole (TDPP) derivatives functionalized with benzoxazole (R-BOX) and dicyanothiophene (R-TCN) groups was carried out using femtosecond transient absorption spectroscopy to understand their excited-state dynamics in solution and thin films.* In chloroform solution, R-BOX showed strong fluorescence with rapid relaxation back to the ground state, while R-TCN exhibited pronounced vibronic and structural relaxation followed by efficient intersystem crossing with an estimated triplet yield of approximately 20%. In thin-film form, both derivatives displayed significantly accelerated singlet-state decay compared to solution, indicating enhanced intermolecular interactions. Long-lived transient spectral signatures initially attributed to triplet-state formation were later identified as laser-induced thermal artefacts through detailed temperature-dependent analysis. The study demonstrates how molecular rigidity and substituent engineering strongly influence relaxation pathways and excited-state behavior in TDPP systems. Furthermore, the work highlights the importance of distinguishing genuine photophysical processes from thermal effects in ultrafast spectroscopic measurements. These findings provide valuable guidelines for the design of advanced organic semiconductors for applications in OFETs, memristors, photovoltaics, and OLED technologies.
References:
* Y. R. Panthi, A. Thottappali, P. Horáková and L. Kubáč, ChemPhysChem, 2024, 25, e202300872.
