Quantum confined CdTe thin films were deposited on nanocrystalline (nc-) TiO2 or on fluorine doped SnO2 (FTO) glass using successive ionic layer adsorption and reaction (SILAR) by successively dipping substrates in aqueous solutions of Cd2+and Te2- prepared in-situ under inert atmosphere. The absorbance of CdTen increased and the absorbance edge shifted to the red with increasing SILAR cycles (n) consistent with quantum size effects. SEM imaging revealed growth of a mesoporous CdTe film on FTO or deposition on the nc-TiO2 particles surface, and XRD patterns indicated cubic CdTe structure. The films photoelectrochemical behavior was studied in alkaline selenide compared to alkaline sulfide electrolyte. While sulfide is not a suitable hole scavenger leading to anodic dissolution, the CdTe films exhibited significant stability and photocurrent generation in the presence of selenide, with an incident photon-to-current-conversion-efficiency (%IPCE) reaching 16% at 460 nm and 9 % at 500 nm at CdTe10/nc-TiO2 in Se2-, compared to 1 % and 0.5% in S2-, respectively. EDX spectra revealed incorporation of Se in the films after hours of illumination at 500 nm under bias, but the photocurrent was stable decreasing by only 5-7%. The results are attributed to effective quenching of the anodic dissolution of CdTe by Se2- scavenging the hole, and a slow growth of a protective overlayer possibly of CdTe1-xSex that does not block photocurrent generation. Fluorescence quenching measurements at CdTe quantum dots capped with mercaptopropionic acid confirmed that Se2- is an effective hole scavenger for Q-CdTe.

Quantum confined CdTe film deposition by successive ionic layer adsorption and reaction (SILAR) and photoelectrochemical stability with Se<sup>2-</sup> as a hole scavenger

248th National Meeting (2014)

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Quantum confined CdTe film deposition by successive ionic layer adsorption and reaction (SILAR) and photoelectrochemical stability with Se2- as a hole scavenger

Quantum confined CdTe film deposition by successive ionic layer adsorption and reaction (SILAR) and photoelectrochemical stability with Se^2- as a hole scavenger