Poly(3-hexylthiophene) (P3HT) is a promising hole transport material (HTM) for perovskite solar cells (PSCs), but poor contact and recombination at the P3HT/perovskite interface limit efficiency. A molecular bridge, MDN, was designed to address this. MDN's malononitrile group anchors the perovskite, while the triphenylamine group forms π-π stacking with P3HT, creating a charge transport channel and passivating defects. PSCs with MDN-doped P3HT (M-P3HT) achieved a 22.87% power conversion efficiency (PCE), significantly higher than with pristine P3HT. The unencapsulated device showed enhanced long-term stability, retaining 92% of its initial efficiency after two months at 75% RH and one month at 85% RH.
