Ionic high-performance light harvesting and carrier transporting OPV materials

Abstract

In this Proceedings paper, we report on the synthesis of a family of polythiophene-based conjugated polyelectrolytes, both homopolymers and random copolymers varying in the building block ratio and counter ions, toward a better fundamental understanding of the structure-property relations of these ionic derivatives in organic photovoltaics. One of the ionic homopolymers was successfully implemented as a donor material in fully solution-processed efficient bi-layer solar cells (up to 1.6% PCE in combination with PC 71 BM) prepared by the low impact meniscus coating technique. On the other hand, these imidazolium-substituted polythiophenes were also applied as materials for electron transport layers (ETLs), boosting the I-V properties of PCDTBT:PC 71 BM solar cell devices up to average PCE values of 6.2% (~20% increase), which is notably higher than for previously reported ETL materials. Advanced scanning probe microscopy techniques were used to elucidate the efficiency enhancing mechanism.

Effect of Spacer Length and Solvent on the Concentration-Driven Aggregation of Cationic Hydrogen-Bonding Donor Polythiophenes

“…The first CPEs were thiophene-based and have been used in solution as fluorescence-based sensors for measuring temperature, solvent polarity, pH, and also chemical and biochemical species. ,,− Different CPEs have been used in solid-state applications to build: (i) electroactive multilayer devices using layer-by-layer assembly of ionic species; − (ii) electrode–buffer layers in optoelectronic devices; − and (iii) active layers in hybrid organic solar cells, using anionic thiophene-CPEs. , In recent years different CPEs have been “revisited” because of their interesting surface properties, which are linked to their charged nature, for example, their capability to show permanent dipoles when applied on top of different substrates. , …”