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

Abstract

In pursuit of efficient quantum dot (QD)-sensitized solar cells based on mesoporous TiO(2) photoanodes, a new procedure for preparing selenide (Se(2-)) was developed and used for depositing CdSe QDs in situ over TiO(2) mesopores by the successive ionic layer adsorption and reaction (SILAR) process in ethanol. The sizes and density of CdSe QDs over TiO(2) were controlled by the number of SILAR cycles applied. After some optimization of these QD-sensitized TiO(2) 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/m(2) 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 TiO(2) film was combined with an organic hole conductor, spiro-OMeTAD, and shown to exhibit a promising efficiency of 1.6% at 100 W/m(2) in inorganic/organic hybrid all-solid-state cells.

Modeling High-Efficiency Quantum Dot Sensitized Solar Cells

“…14,15 So far research in this field has focused mainly on showing the validity of the concept and increasing efficiencies and photocurrents of these cells, which were rather low in the beginning. Different semiconductor materials, semiconductor preparation, attaching modes, surface treatments, electrolyte configurations, counter-electrodes, to cite some examples, have been checked in order to improve the performance of QDSCs, but there are few examples of a complete characterization and modeling of photovoltaic devices, 14,16,17 beyond the conventional currentϪpotential (JϪV) curves and incident photon-to-current efficiency (IPCE) measurements. As a consequence no clear model and characterization method have been developed to identify unambiguously the limiting factors in these devices and the real effect in the cell performance of each of the modifications that have been explored.…”

The Application of Inorganic Nanomaterials in Dye-Sensitized Solar Cells

“…This method has been used in particular to prepare metal sulfides, but recently it has been expanded to metal selenides and tellurides. For example, Grätzel et al deposited the CdSe and CdTe QDs in situ onto mesoporous TiO 2 films using SILAR approach (Lee et al, 2009b). After some optimization of these QD-sensitized TiO 2 films in solar cells, over 4% overall efficiency was achieved at 100 W/m 2 with about 50% IPCE at its maximum (Lee et al, 2009b).…”

CdS nanoparticles decorated anatase TiO 2 nanotubes with enhanced visible light photocatalytic activity

“…Second, the quantum efficiency of TNT in photocatalytic reactions under UV light irradiation is very low. To improve the visible light photocatalytic activity, many efforts have been made, such as dye sensitisation [19], doping [20][21][22][23][24], and coupling with low bandgap semiconductors like PbS [25], CdTe [26], CdSe [27], ZnFe 2 O 4 [28], Cu 2 O [29], and CdS [18,[30][31][32]. Among the low bandgap semiconductors, CdS has attracted much attention, it can be excited by visible light to produce electrons and holes due to the narrow band gap of 2.42 eV [33].…”