Comparison of solar cells sensitised by CdTe/CdSe and CdSe/CdTe core/shell colloidal quantum dots with and without a CdS outer layer

• Published in: Thin solid films Vol. 560; pp. 65 - 70
• Main Authors: McElroy, N., Page, R.C., Espinbarro-Valazquez, D., Lewis, E., Haigh, S., O'Brien, P., Binks, D.J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 02.06.2014; Elsevier
• Subjects: Applied sciences; Cadmium chalcogenide; Cadmium selenides; Cadmium tellurides; Cross-disciplinary physics: materials science; rheology; Energy; Exact sciences and technology; Intermetallics; Materials science; Nanoscale materials and structures: fabrication and characterization; Natural energy; Other semiconductors; Other topics in nanoscale materials and structures; Photovoltaic cells; Photovoltaic conversion; Physics; Quantum dots; Qunatum dots; Shells; Solar cell; Solar cells; Solar cells. Photoelectrochemical cells; Solar energy; Specific materials; Titanium dioxide; Type-II quantum dot; Zinc; Solar cell; Cadmium chalcogenide; Type-II quantum dot; Quantum dot; Blende structure; Core shell structure; Photoluminescence; X ray diffraction; Porous material; Mesoporosity; Absorption spectrum; Zinc; Photovoltaic cell; Near infrared radiation; Electrolyte; II-VI semiconductors; Platinum; Scanning transmission electron microscopy; Nanostructured materials; Absorption edge; Crystalline structure
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2013.10.085

CdTe/CdSe and CdSe/CdTe core/shell colloidal quantum dots, both with and without a second CdS shell, have been synthesised and characterised by absorption and photoluminescence spectroscopies, scanning transmission electron microscopy and X-ray diffraction. Each type of quantum dot had a zinc blende crystal structure and had an absorption edge in the near-infrared, potentially enabling the more efficient exploitation of the solar spectrum. Each was used to sensitise a photovoltaic cell of a ‘Grätzel-type’ design consisting of the dots coated onto mesoporous TiO2, a sulphur-based electrolyte and a platinum top electrode. The photovoltaic efficiency of the cells was found to be greater for Type-II dots as compared to the quasi-Type-II dots. However, the efficiency was reduced on the addition of an outer CdS shell indicating that it acts as a barrier to charge extraction. •CdTe/CdSe and CdSe/CdTe type-II quantum dots were synthesised and characterised.•A passivating CdS final shell was added to both orientations to improve stability.•Grätzel-type photovoltaic cells were made and performance tested for all examples.•CdTe-cored samples outperformed their CdSe-cored analogues.•The addition of a CdS passivating layer was detrimental to performance.