Journal Article morphology perovskite solar cells PCPDTBT (poly{[4,4-bis(2-ethylhexyl)-cyclopenta-(2,1-b;3,4-b')dithiophen]-2,6-diyl-alt-(2,1,3-benzo-thiadiazole)-4,7-diyl}) Research Support, U.S. Gov't, Non-P.H.S. all-perovskite tandem solar cells amorphous silicon charge generation charge transfer states crystallization degradation driving force excess energy geminate recombination hybrid multijunctions low bandgap polymers low-bandgap polymers non-radiative interface recombination organic solar cells photoluminescence piperazinium iodide proton irradiation radiation hardness recombination losses record efficiencies self-healing solvent vapor annealing spectroelectrochemistry thin-film solar cells triple-halide wide-bandgap perovskite