Photoconductivity in Metal-Organic Framework Thin Films
Liu, X. / Kozlowska, M. / Okkali, T. / Wagner, D. / Higashino, T. / Fu, Z. / Zhang, Q. / Imahori, H. / Bräse, S. / Wenzel, W. / Wöll, C. / Heinke, L. (2019)
Angew. Chem. Int. Ed. , 2019, DOI.org/10.1002/anie.201904475
- Date: April 2019
Photoconductivity is a characteristic property of semi‐conductors, enabling various applications such as photoresponsive transistors and light‐sensing. Here, we present a photo‐conducting crystalline metal‐organic framework, MOF, thin film with an on‐off photocurrent ratio of two orders of magnitude. These oriented, surface‐mounted MOF thin films, SURMOFs, contain porphyrin in the framework backbone and C60 guests, loaded in the pores using a layer‐by‐layer process. By comparison with results obtained for reference MOF structures and based on density‐functional theory calculations, we conclude that donor‐acceptor interactions between the porphyrin of the host MOF and the C60 guests give rise to a rapid charge separation. Subsequently, holes and electrons are transported through separate channels formed by porphyrin and by C60, respectively. The ability to tune the properties and energy levels of the active molecules, porphyrin and fullerene, combined with the controlled organization of donor‐acceptor pairs in this regular framework offers a huge potential to increase the photoconduction on‐off ratio in future work.