A low-cost thiophene-based hole transport material containing azomethine as a bridge for perovskite solar cells or absorber organic solar cells: a Theoretical study

Four thiophene-based organic molecules, H1-H4, featuring diverse thiophene central cores, triphenylamine side groups, and amide bridges, were designed as D-π-A-π-D type hole-transporting materials (HTMs) for use in perovskite solar cells (PSCs).

According to our findings, the proposed and produced HTMs demonstrated outstanding coherence in terms of charge carrier transit, dispersion, and excitation qualities that are perfectly suitable for strong hole mobility. The findings reveal that acceptor moieties functionalized HTMs exhibit minimal optical absorption in the visible portion with negligible overlap with the active perovskite layer, indicating suitable optoelectronic and photophysical profiles of effective HTMs. Additionally, the results demonstrate excellent band alignment with the active perovskite layer with fitting HOMO energy levels.

This result is comparable to state-of-the-art materials, such as Spiro-OMeTAD, in a similar comparison. Cost estimates indicate that the material cost is approximately an order of magnitude lower for EDOT-OMeTPA (HR), resulting in a negligible contribution to the peak cost per watt of USD 0.004 W⁻¹. Furthermore, the high synthetic accessibility of EDOT-OMeTPA also reduces the use of toxic chemicals, thereby significantly reducing its environmental impact. Our results pave the way towards low-cost, environmentally friendly, and efficient HTMs.

Finally, our findings provide a molecular-level understanding of creating new HTM design strategies for enhanced photovoltaic features. To achieve higher efficacy, thiophene-based HTMs are intended to be incorporated into upcoming solar cell technologies