Journal Article N-heterocyclic carbene ligands additive-free organic solar cells all-polymer solar cells carrier balance charge transport concentration quenching deep-blue phosphorescence dopant-free perovskite solar cells double-network structure electroluminescent devices exciton dissociation fluorination high efficiency hole transporting materials ionogels new multirole π-conjugated polymers organic light-emitting diodes organic solar cells perovskite solar cells small molecules solar cells stretchable optoelectronics theoretical studies time-resolved microwave conductivity