Strategical designing of diketopyrrolopyrrole-thiophene based donor-acceptor type organic oligomers and study their transport properties: A DFT/TD-DFT perspective

Herein, we have designed and studied a series of DPP based D-A type oligomers. We have joined the DPP (acceptor) and thiophene (donor) by an azomethine linkage to facilitate the charge transportation. Dihedral angles, Delta(H-L), IP, EA, lambda, k(CT), mu(hop) values and spectral properties are calculated to examine the effect of the substituents (+ I and - I groups). We have also calculated the pi-coherence length of the oligomers. Results show that both electron withdrawing and donating substituents are capable of better tuning the optoelectronic properties of the proposed oligomers. In short, our designed materials will act as potential candidates for fabrication of optoelectronic devices.