Polymers with Large Spin-Orbit Coupling

The dynamics of spin singlet and triplet excitons in p-conjugated polymers define their performance as optically active layer in organic light-emitting diodes (OLEDs) and organic photovoltaic (OPV) cells. As an example, if both triplet and singlet excitons can be used in OLEDs to convert electrical energy to electroluminescence (EL) emission, then the fraction of excitons that potentially can emit light may reach 100 % [1]. Similarly in OPV based on donor/acceptor (D–A) blends, the photogenerated singlet exciton in the polymer donor domains may recombine before reaching the D–A interface, because of its relatively short lifetime (~100 ps). In contrast, because of the much longer lifetime (~5 ms), triplet excitons could reach the D–A interface with larger probability and thus could potentially be the answer to this loss mechanism [2]. Therefore, both OLED and OPV technologies may substantially benefit from the proper use of the spin triplet states. Alas, because the spin-orbit coupling (SOC) in polymers is typically very weak (