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Pathways for Improving the Photovoltaic Efficiency of Porphyrin and Phosphorene Antidot Lattice Nanocomposites: An Insight from a Theoretical Study

Kar, Moumita, Sarkar, Ritabrata, Pal, Sougata, Sarkar, Pranab
Journal of physical chemistry 2019 v.123 no.9 pp. 5303-5311
encapsulation, moieties, nanocomposites, photosensitizing agents, porosity, porphyrins, solar cells
The porosity of a newly synthesized phosphorene antidot lattice (PAL) is promising for encapsulating the porphyrin molecule and thus shows a versatile route to fabricate porphyrin/PAL nanocomposites. We herein explored the photovoltaic performance of a tetraphenylporphyrin (TPP)/PAL composite system. Interestingly, TPP/PAL composites show type-II staggered band alignment where a conduction band resides on TPP and a valence band resides on PAL. However, the driving force for hole transfer to PAL from TPP is very small (∼0.02 eV), implying faster charge recombination inside the TPP itself. To overcome the unpleasant situation, we adopted a substitution strategy at TPP and PAL components. As porphyrins are effective photosensitizers due to the π-conjugated electronic structure, we attached an electron-donating group (−NH₂) to the TPP moiety and an electron-withdrawing group (−CN) at the edge of PAL. The composites show a high photovoltaic performance of up to 13.5%, making them competitive with other two-dimensional heterostructural solar cells. Interestingly, if the starting material is TiO-TPP instead of TPP, then one may achieve the intended type-II band alignment and open up a new route to improve the efficiency without functionalizing the TPP or PAL.