Redox‐Active β ‐Tetrathiophenyl Porphyrins as Next‐Generation Hole‐Transport Materials in Perovskite Photodetectors

ABSTRACT

We report the design, synthesis, and comprehensive characterization of a series of electron‐rich β ‐tetrathiophenyl porphyrins, MTPP(SPh) ₄ (M = 2H, Co, Ni, Cu, and Zn), developed as solution‐processable hole‐transporting materials (HTMs) for perovskite photodetectors. Single‐crystal XRD and DFT calculations reveal prominent macrocyclic nonplanarity induced by bulky ‐SPh substituents, resulting in red‐shifted optical transitions, reduced HOMO‐LUMO gaps, and multiple reversible redox processes. When integrated as interfacial hole transport layers (HTLs) in FA _0.9 Cs _0.1 Pb(I _0.94 Br _0.06 ) ₃ ‐based lateral photodetectors, these porphyrins significantly suppress dark current, enhance charge extraction, and reduce transport resistance, as supported by J ‐ V analysis and impedance spectroscopy. Among the series, ZnTPP(SPh) ₄ and NiTPP(SPh) ₄ porphyrins exhibit the highest performance, achieving broadband responsivity (400–720 nm) with maximum detectivities of 1.43 × 10 ¹¹ and 1.10 × 10 ¹¹ Jones, respectively. These results establish β ‐tetrathiophenyl porphyrins as a structurally tunable and efficient class of HTMs, offering a minimalistic yet powerful strategy for high‐performance, stable perovskite photodetectors.