Molecular Interface Engineering via Triazatruxene‐Based Moieties/NiOx as Hole‐Selective Bilayers in Perovskite Solar Cells for Reliability

Interface engineering is an effective approach to decrease nonradiative recombination and the energy barrier at the perovskite/hole transporting layer (HTL) interfaces. To overcome such limitations, an organic semiconductor (DTT‐EHDI 2 ) is proposed, which is, composed of dithienothiophene (DTT) as the core and a planar triazatruxene incorporating an alkyl chain as the side group. This is noted to be an effective interfacial layer for inverted planar perovskite solar cells (PSCs). The altered interface effectively minimizes the detrimental charge recombination and tailors the photoinduced charge transfer dynamics at the interface of the inorganic HTL/perovskite. The π‐conjugation in DTT‐EHDI 2 induces high hole mobility and electrical conductivity via electron‐donating properties and strong π–π intermolecular interaction. The synergetic approach leads to a substantial performance enhancement in dopant‐free DTT‐EHDI 2 ‐based inverted planar PSCs, achieving 18.15% power conversion efficiency with negligible hysteresis effect. The present approach provides an effective direction of the cost‐effective thiophene derivative as an interfacial agent to escalate the optoelectronic performances in photovoltaics.