Photocurrent vibrationally promoted electronic resonance spectroscopy for probing vibronic interactions in optoelectronic materials

Recently, interactions between electronic and vibrational processes have been proposed to control various phenomena in a wide range of optoelectronic materials. Supposedly, these vibronic interactions may play the key role in physics of semiconducting materials for flexible soft photovoltaics by influencing optical, electrical, and other photovoltaic properties. Yet, their exact role in performance of real functional photovoltaic devices remains unclear, because of the current limitations of experimental and computational techniques. Here we develop a new method for studying vibronic interactions in functional optoelectronic materials based on the state-of-art combination of ultrafast spectroscopies and photocurrent detection techniques — photocurrent vibrationally promoted electronic resonance (photocurrent VIPER). The applicability of this technique is demonstrated by revealing the coupling of certain organic cation modes and inorganic lattice distortion in FaPbBr3 perovskite.