Inhibiting Interfacial Charge Recombination for Boosting Power Conversion Efficiency in CdSe{Au} Nanohybrid Sensitized Solar Cell

To boost the power conversion efficiency (PCE) of quantum dot solar cell (QDSC) by long-lived charge separated state, we are introducing CdSe­{Au} nanohybrid material (NHM) which acts as a better light harvester than CdSe quantum dot (QD) alone. Steady state absorption studies show broadening of the absorption band of CdSe­{Au} NHM up to 800 nm. The steady state and time-resolved luminescence studies reveal ultrafast electron transfer from CdSe QD to Au nanoparticles (NPs), forming a charge separated state. The measured PCE of the CdSe­{Au} NHM is 4.39% which is significantly higher than pure CdSe QDs (3.37%). The enhancement of PCE has been explained by femtosecond transient absorption (TA) and electrochemical impedance spectroscopy (EIS). The ultrafast TA studies suggest subpicosecond electron transfer from CdSe QDs to Au NP and slower charge recombination in NHM. Interestingly 3 times higher recombination resistance at the interface of TiO₂–CdSe­{Au} as compared to TiO₂–CdSe is shown by EIS measurements, which has also explained the enhancement of PCE for the NHM. To the best of our knowledge this is the first report of PCE for any kind of metal–semiconductor NHM