Porphyrinoids for Molecular Photovoltaics

In this contribution, hexachloro subphthalocyanines SubPcCl6-X bearing different axial substituents (X) have been synthesized and used as novel electron acceptors in bulk-heterojunction organic solar cells . Solar cells with subphthalocyanines as the electron acceptors and PTB7-Th as the electron donor exhibit a power conversion efficiency up to 4% and an external quantum efficiency approaching 60% benefitting from significant photocurrent contribution from both electron donor and acceptor. These results indicate a promising prospect of developing non-fullerene acceptors based on subphthalocyanines and structurally related systems for highly efficient solution processed organic solar cells [1]. On the other hand, an unsymmetrical, push–pull porphyrazine derivative bearing an isoindole-4-carboxylic acid moiety (TT112) have been synthesized and incorporated in a dye-sensitized solar cell (DSSC). The device, which constitutes the first example of a porphyrazine-sensitized solar cell, exhibits a maximum power conversion efficiency of 3.4% [2]. Finally, easily accessible tetra-5-hexylthiophene-, tetra-5-hexyl-2,2’-bisthiophene-substituted zinc phthalocyanines (ZnPcs) have been employed as hole transporting materials (HTMs) in mixed-ion perovskite [HC(NH 2 ) 2 ] 0.85 (CH 3 NH 3 ) 0.15 Pb(I 0.85 Br 0.15 ) 3 solar cells reaching the highest power conversion efficiency (PCE) reported so far for phthalocyanines. The resulting photovoltaic performance was strongly influenced by both, individual optoelectronic properties of ZnPcs and the aggregation of these tetrapyrrolic semiconductors in the HTM layer. The optimized devices exhibited a record PCE of 17.5% for tetra-5-hexylthiophene-based analogue under standard global AM 1.5 illumination. These results boost up the potential large-scale applications of solution-processed ZnPc derivatives as stable and economic hole-transport materials, opening new frontiers towards a realistic, efficient and inexpensive energy production [3]. [1] C. Duan, G. Zango, M. García Iglesias, F. J. M. Colberts, M. M. Wienk, M. V. Martínez-Díaz, R. A. J. Janssen, T. Torres, Angew. Chem. Int.. Ed. Engl. 2017 , in press. [2] J. Fernández-Ariza, M. Urbani, M. Grätzel, M. S. Rodríguez-Morgade, M. K. Nazeeruddin, T. Torres, ChemPhotoChem 2016 , DOI: 10.1002/cptc.201600004 [3] K. T. Cho, O. Trukhina, C. Roldán-Carmona, M. Ince, P. Gratia, G. Grancini, P. Gao, T. Marszalek, W. Pisula, P. Y. Reddy, T. Torres, M. K. Nazeeruddin, Adv. Energ. Mat. 2016