Tailoring of the thieno [3,2-b] thiophene-based molecule towards promising hole transporting materials for perovskite solar cells

Perovskite solar cells (PSCs) garnered the interest of researchers owing to their affordable fabrication and higher efficiency. Solution-processing hole transporting materials (HTMs) having remarkable charge mobility are highly appreciated for acquiring improved efficiency of PSCs. In this project, we designed five new HTMs (M3A1-M3A5) based on thieno (3,2-b) thiophene by introducing thiophene linkers and terminal acceptors. Our basic purpose was to enhance photovoltaic and opto-electronic attributes for highly efficient PSCs. We employed MPW1PW91/6-31G for computationally investigating tailored HTMs in terms of geometrical, opto-electronic, charge transferal, and photovoltaic parameters. Outcomes demonstrated a bathochromic shift in both gaseous and THF phases. Our tailored HTMs exhibited deeper HOMO levels (-4.81 -> -4.64) along with reduced band gaps (0.94-2.13 eV) as compared to M3-R and Spiro-OMeTAD, referring to improved hole-extraction and solution processing. Lower excitation energies of tailored HTMs lead to minimized energy loss. The reorganization energy of hole (lambda(h)) and electron (lambda(e)) are quite lower than M3-R suggesting higher charge mobility. Greater hole transfer integral (0.14 eV) points toward better hole transportation along with reduced lambda(e) and lambda(h). Considerably greater open-circuit voltage (V-OC) ensures the conspicuous efficiency of PSCs. All the findings validated the effectiveness of the applied strategy for the fabrication of HTMs for future PSCs.