Platinum-acetylide polymers with higher dimensionality for organic solar cells

A new series of platinum(II)-acetylide polymers P1-P3 containing thiophene-triarylamine chromophores of different dimensions were synthesized and their electronic band structures, field-effect charge transport, and application in bulk heterojunction solar cells were evaluated. These materials are soluble in polar organic solvents and show strong absorptions in the solar spectra (with the highest absorption coefficient of 1.59× 10 5cm-1 from thin films), thus rendering them excellent candidates for bulk heterojunction polymer solar cells. The spin-coated polymer thin films showed p-channel field-effect charge transport with hole mobilities of 1.90× 10-5 to 7.86× 10-5cm 2V-1s-1 for P1-P3 and an improved charge carrier transport was found for P2 with higher molecular dimensionality than P1. The dependence of their photovoltaic properties and dimensionality was also investigated. Even if the polymers possess relatively high bandgaps and narrow absorption bandwidths, the highest power conversion efficiency of 2.24% can be obtained based on blends of P3 with [6,6]phenyl-C61-butyric acid methyl ester (PCBM) (1:5, w/w) under AM1.5 simulated solar illumination. The present work indicates that multidimensional polymers exhibit a better photovoltaic performance over the linear polymers under the same measurement conditions and can provide an attractive approach to developing highly efficient conjugated metallopolymers for efficient power generation. KGaA, Weinheim.