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Fabrication and charge‐transfer characteristics of CdS QDs sensitized vertically grown flower‐like ZnO solar cells with CdSe cosensitizers
Author(s) -
Sudhagar P.,
Chandramohan S.,
Kumar R. Saravana,
Sathyamoorthy R.,
Hong ChangHee,
Kang Yong Soo
Publication year - 2011
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201026276
Subject(s) - quantum dot , photocurrent , materials science , optoelectronics , overlayer , chemical bath deposition , solar cell , quenching (fluorescence) , charge (physics) , charge carrier , semiconductor , fabrication , nanotechnology , band gap , chemistry , optics , fluorescence , physics , quantum mechanics , medicine , alternative medicine , pathology
This paper proposes the concept of using bisensitizers (CdS and CdSe) to improve the light‐harvesting capabilities and charge transfer in ZnO photoelectrodes. The novel flower‐like ZnO nanoarrays were grown by chemical bath deposition and they are sensitized with CdS quantum dots (QDs) and a CdSe overlayer. We observed a strong quenching of band‐edge emission following the growth of QDs on ZnO, which is evidence for the occurrence of charge transfer between the QDs and the ZnO. A possible charge‐transfer mechanism is proposed and discussed on the basis of energy‐band alignment. Bisensitized ZnO electrodes resulted in a higher photoconversion efficiency ( η = 1.08%) than that of single CdS QD‐sensitized solar cells ( η = 0.52%). The high photocurrent and improved power conversion are attributed to more charge‐carrier generation facilitated by an extended spectral response and charge injection between the QDs and TiO 2 .Schematic representation of CdS and CdSe bisensitized flower‐like ZnO solar cell structure investigated in this study.