Photovoltaic properties of hole transport materials for organic solar cell (OSC) applications: physiochemical insight and in silico designing

Hole transport materials (HTMs) play a dominant role in enhancing the photovoltaic and optoelectronic properties of solar cells. These materials efficiently transport the hole, which significantly boosts the power conversion efficiencies of solar cells. In order to obtain better photovoltaic materials with efficient optoelectronic characteristics, we theoretically designed five new hole transport materials (Y3D1-Y3D5) after end-capped donor modifications of the recently synthesized highly efficient hole transport material Y3N (R). The relationships among photovoltaic, photophysical, optoelectronic and structural properties of these newly designed molecular models were studied at 6-31G(d,p) basis set and MPW1PW91 functional levels. Time-Dependent Density Functional Theory (TDDFT) and density functional theory (DFT) proved to be excellent approaches for the studied systems. Geometrical parameters, molecular orbitals (MOs), open-circuit voltage (Voc), energy of binding and density of states were calculated. Low reorganization energy (RE) was noted; compared with the parent molecule (Reference/R), the designed molecular models possess high mobility. Molecular electrostatic potential (MEP) also supports our conclusion. Last but not least, the Y3D3:PC61BM complex was also studied to comprehend the role of charge distribution. These analyses showed that our modelled molecules are more efficient than the Y3N molecule. Thus, recommendations are made for experimentalists to develop extremely efficient solar cells in the near future.