Charge carrier dynamics in CdTe/ZnTe core/shell nanocrystals for photovoltaic applications $$^{\S }$$ §

Abstract

CdTe/ZnTe type-II core/shell nanocrystals were synthesized and characterized by the red-shift in the UV-Vis absorption and emission spectra along with the increase in both emission quantum yield and lifetime. The charge carrier dynamics was investigated through ultrafast transient absorption spectroscopy revealing the excited state carrier distribution and the dynamics through which the carriers decay. Upon laser pulse excitation the transient absorption spectrum was characterized by a broad ground state bleach signal in the core/shell nanocrystals in accord with the absorption spectra. Slower electron cooling was found in the core/shell nanocrystals compared to the CdTe core due to the type-II band-alignment that decouples the electron from hole preventing Auger-assisted electron cooling process. The recombination was found to be much slower in the core/shell nanocrystals due to the better surface passivation provided by the ZnTe shell eliminating the surface trapping process. The low band-gap CdTe based nanocrystals with a charge separated state are a viable candidate for photovoltaic applications and finally, we have investigated the potentiality of the synthesized nanocrystals as sensitizers in quantum dot solar cells.

Improving the Power‐Conversion Efficiency through Alloying in Common Anion CdZnX (X=S, Se) Nanocrystal Sensitized Solar Cells

“…[15,31,[36][37][38][39][40][41] Briefly, TiO 2 photoanodes with transparent layer were prepared through doctor blade technique followed by annealing at 450°C for 30 minutes. [15,31,[36][37][38][39][40][41] Briefly, TiO 2 photoanodes with transparent layer were prepared through doctor blade technique followed by annealing at 450°C for 30 minutes.…”

“…The device fabrication protocol used here was originally developed by Zhong et al and subsequently modified by our group. [15,31,[36][37][38][39][40][41] Briefly, TiO 2 photoanodes with transparent layer were prepared through doctor blade technique followed by annealing at 450°C for 30 minutes. Then the photoanodes were coated with scattering TiO 2 layer and annealed again at 450°C for 30 minutes.…”