Design of new bithieno thiophene (BTTI) central core-based small molecules as efficient hole transport materials for perovskite solar cells and donor materials for organic solar cells

This present study focuses on designing five bithienothiophene (BTTI) central core-based small molecules (MPA-BTTI-A1-MPA-BTTI-A5) in exploring the optoelectronic properties to ensure their potentiality as donor candi-dates for organic solar cells (OSCs) and HTMs. MPA-BTTI-A1 and MPA-BTTI-A3 are tailored by the replacing thiophene-bridge end-capped acceptors on one side terminal of reference (MPA-BTTI-R). Similarly, MPA-BTTI-A2, MPA-BTTI-A4 and MPA-BTTI-A5 have been designed by employing the same strategy on both side termi-nals. To ascertain stable geometric structures, CAM-B3LYP/6-311G (d,p) is selected and used in all computa-tional simulations. The MPA-BTTI-A1 exhibits the least energy gap of 1.69 eV with greatest lambda max at 722 nm in dichloromethane (DCM) and highest dipole moment of 19.59 D in DCM solvent, indicating excellent miscibility as compared to the model/reference. All newly fabricated molecules (MPA-BTTI-A1-MPA-BTTI-A5) suggest excellent operational efficiency due to their higher Voc also relatively high-power conversion efficiency (PCE) in comparison to reference. Also, all fabricated molecules are attributed with a greater estimated PCE of range (20.74-40.3%), than reference (PCE = 16%). The highest electron mobility of 0.0871 eV is observed in MPA-BTTI-A3 andMPA-BTTI-A2 exhibits the highest hole mobility of 0.1334 eV. Hence, the modification scheme is a promising way in designing proficient photovoltaic materials, paving ways for new design and advancement of a small-molecule HTMs for donor contributors for organic solar cells (OSCs) and in PSCs.