Supramolecular organic-inorganic domains integrating fullerene-based acceptors with polyoxometalate-bis-pyrene tweezers for organic photovoltaic applications

A strategy to improve organic photovoltaics, and to enhance the device efficiency, builds on the design of interfacial layered (IFL) materials implementing the performance of the photoactive acceptor/donor system. A novel IFL blend has been engineered by a supramolecular organic-inorganic heterojunction integrating polyoxometalate-bis-pyrene (pyrPOM) receptors that can selectively bind fullerene-based acceptors through pi-pi interactions and in particular the most used phenyl-C61-butyric acid methyl ester (PCBM) PCBM. The resulting pyrPOM@PCBM IFL, assembled by means of the Langmuir-Blodgett approach, has been fully characterized both in solution and on solid supports by means of the Langmuir-Schaefer method, featuring a high dielectric function, good polarizability and piezo-responsive behavior, which suggest ferroelectric properties. An organic solar cell is realized interposing the IFL between poly(3-hexylthiophene) (P3HT) as polymer donor and the PCBM acceptor layers, thus enhancing the open circuit voltage of the solar device by about 34% under an applied bias of +/- 5 V.