van der Waals Epitaxial Growth of 2D Metal–Porphyrin Framework Derived Thin Films for Dye‐Sensitized Solar Cells

In this work, monolithic, crystalline, porous, and oriented porphyrin thin films are grown using a novel van der Waals layer‐by‐layer (lbl) epitaxial growth protocol, yielding an unusual AB‐stacking motif of these interesting macrocycles units. Subsequently, these surface‐mounted metal‐organic frameworks (SURMOFs) are transformed by thermal treatment to yield well‐performing counter electrodes (CEs) for dye‐sensitized solar cells. During this calcination, the heterocyclic macrocycles are metalated, yielding compact, homogeneous, and very stable metalloporphyrin thin films (ZnTCPP‐C) with excellent CE performance. For thin films fabricated using three lbl cycles (thickness ≈17 nm), the power conversion efficiency is found to amount to 5.63%, making it a promising candidate to replace Pt CE (6.72%). Such calcined SURMOFs carry huge potential for fabricating electronic and photovoltaic devices. A novel van der Waals epitaxial growth method for growing oriented and highly homogeneous 2D metal–porphyrin framework thin films is reported. After thermal treatment, the compact and homogeneous zinc [5,10,15,20‐(4‐carboxyphenyl) porphyrin (ZnTCPP) derived thin film zinc [5,10,15,20‐(4‐carboxyphenyl) porphyrin after calcination (ZnTCPP‐C) as counter electrode in dye‐sensitized solar cells exhibits remarkable power conversion efficiency. Such thin films carry huge potential for fabricating electronic and photovoltaic devices.