Abstract:
Quantum dots have attracted extensive attention in different applications including
light emitting diodes, photodetectors, photovoltaic cells and spectrometers.
Quantum dot-sensitized solar cells (QDSSCs) have gained more attention recently
in the area of solar power conversion systems due to their less production cost and
the excellent properties of quantum dots such as ability of multiple exciton
generation (MEG), tuneable energy gap due to the quantum confinement effect and
high molar extinction coefficients. The working principle and structure of QDSSC
is similar to the dye-sensitized solar cell. Only difference between these solar cells
is the sensitizer. CdS quantum dot is an II-VI type semiconductor with a bulk
bandgap of 2.42 eV. CdS quantum dots are used for the QDSSC application due to
its wide range absorption in the visible region. CdS quantum dot – sensitized solar
cells are the low-cost photovoltaic cells. CdS quantum dots have been deposited
on TiO2 electrodes by using successive ionic layer adsorption and reaction
(SILAR) technique. Optical and electrical characterizations of the electrodes and
solar cells have been studied with different amounts and sizes of CdS quantum
dots. In order to fabricate a better CdS quantum dot – sensitized solar cell, number
of SILAR cycles has been optimized. CdS QDSSC fabricated with 7 SILAR cycles
shows a better efficiency of 0.674% with a short circuit current density of 5.148
mA cm-2
.
