Significant efficiency enhancement of CdSe/CdS quantum-dot sensitized solar cells by black TiO2 engineered with ultrashort filamentating pulses

Abstract While the efficiency of quantum dot sensitized solar cells (QDSSCs) has been long limited by photogenerated electron extraction of photoanode, we propose here an alternative approach for boosting the light harvesting efficiency of QDSSCs, which is based on the modifications of the TiO2 photoanode absorbance and impedance by irradiating crystalline TiO2 nanoparticles with intense femtosecond laser pulses propagating in the filamentation regime. We demonstrate that a two-fold enhancement of the power conversion efficiency in CdSe/CdS-cosensitized solar cells is unambiguously achieved with the produced “black” TiO2 nanoparticles as photoanode, which allows for the light absorption in the spectral range of 240-2500 nm and enables possible facilitation of electron transport. Our results offer a viable route to boosting QDSSCs efficiency that is normally realized by optimizing the photoanode material morphology and structure as well as quantum dot species in QDSSCs.