**Abstract**

Recently, donor-acceptor type molecule that contains electron-rich (D) and electron-deficient (A) moiety has emerged as an interesting approach of molecular design strategy to develop organic light-emitting diodes (OLEDs) and non-linear optical (NLO) devices. In this work, we report a theoretical investigation based on two donor-acceptor (D-A) type small π-conjugated molecules based on dithieno [3,2-b: 2<sup>0</sup> ,30 -d] pyrrole (DTP) and anthracene derivatives. All of the theoretical calculations were performed by Density Functional Theory (DFT) approach at B3LYP/6-31 g(d) level of theory. The structural, electronic, optical and charge transfer properties were investigated. The effect of acceptor blocks (DPA and DTA) on the molecular characteristics was elucidated. The obtained results clearly show that the studied compounds exhibit non-coplanar structures with low electronic band gap values. These relevant structures exhibited important optical absorption and intense emission in the green-yellow region. NLO investigation based on static polarizability (α0), first-order hyperpolarizability (β0) and second-order hyperpolazabilty (ɣ0) demonstrated that the studied materials exhibit excellent NLO properties. Thus, the designed materials showed promising capabilities to be utilized in OLED and NLO applications.

**Keywords:** DTP, Anthracene, DFT, Optical properties, OLEDs, NLO properties
