Efficient CdSe Quantum Dot-Sensitized Solar Cells Prepared by an Improved Successive Ionic Layer Adsorption and Reaction Process

• Published in: Nano letters Vol. 9; no. 12; pp. 4221 - 4227
• Main Authors: Lee, HyoJoong, Wang, Mingkui, Chen, Peter, Gamelin, Daniel R, Zakeeruddin, Shaik M, Grätzel, Michael, Nazeeruddin, Md. K
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 09.12.2009
• Subjects: Adsorption; Applied sciences; Cadmium Compounds - chemistry; Cross-disciplinary physics: materials science; rheology; Crystallization - methods; Electric Power Supplies; Electronics; Energy; Equipment Design; Equipment Failure Analysis; Exact sciences and technology; Ions; Macromolecular Substances - chemistry; Materials science; Materials Testing; Molecular Conformation; Molecular electronics, nanoelectronics; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Nanostructures - chemistry; Nanostructures - ultrastructure; Nanotechnology - instrumentation; Natural energy; Particle Size; Photovoltaic conversion; Physics; Quantum Dots; Selenium Compounds - chemistry; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Solar cells. Photoelectrochemical cells; Solar Energy; Surface Properties; Solar cells; Voltage measurement; Ethanol; Organic conductors; Quantum dots; Photoelectrochemical cells; Hybrid material; Porous materials; Cobalt; Mesoporosity; Optimization; Transients; Cadmium selenides; Thin films; Redox couple; Organic-inorganic hybrid materials; Adsorption; II-VI semiconductors; Cadmium tellurides; Titanium oxide; Nanostructured materials
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl902438d

In pursuit of efficient quantum dot (QD)-sensitized solar cells based on mesoporous TiO2 photoanodes, a new procedure for preparing selenide (Se2−) was developed and used for depositing CdSe QDs in situ over TiO2 mesopores by the successive ionic layer adsorption and reaction (SILAR) process in ethanol. The sizes and density of CdSe QDs over TiO2 were controlled by the number of SILAR cycles applied. After some optimization of these QD-sensitized TiO2 films in regenerative photoelectrochemical cells using a cobalt redox couple [Co(o-phen)3 2+/3+], including addition of a final layer of CdTe, over 4% overall efficiencies were achieved at 100 W/m2 with about 50% IPCE at its maximum. Light-harvesting properties and transient voltage decay/impedance measurements confirmed that CdTe-terminated CdSe QD cells gave better charge-collection efficiencies and kinetic parameters than corresponding CdSe QD cells. In a preliminary study, a CdSe(Te) QD-sensitized TiO2 film was combined with an organic hole conductor, spiro-OMeTAD, and shown to exhibit a promising efficiency of 1.6% at 100 W/m2 in inorganic/organic hybrid all-solid-state cells.