Our review provides a brief overview of efficient QDs, synthesis, strategies for designing QDs based PV cells, shortcomings, and suggestions to overcome the drawbacks that limit efficiency.
How efficient are quantum dot solar cells?
We demonstrate improved performance of quantum dot solar cells (QDSCs) by type-II InAs/GaAsSb structure. With a moderate Sb composition of 18% and high quality QDs, a high efficiency of 17.31% under AM1.5 G illumination is achieved, showing an improvement of 11.25% in efficiency relative to type-I InAs/InGaAs QDSC.
The most important process in all the QD solar cells for reaching very high conversion efficiency is the multiple electron–hole pair production in the photoexcited QDs; the various cell configurations simply represent different modes of collecting and transporting the photogenerated carriers produced in the QDs.
What is a QD solar cell?
Three QD solar cell configurations are described: (1) photoelectrodes comprising QD arrays, (2) QD-sensitized nanocrystalline TiO 2, and (3) QDs dispersed in a blend of electron- and hole-conducting polymers.
Why do solar cells have a quasi-Fermi-level split?
By sequentially absorbing two sub-bandgap photons, electrons in VB can be pumped to the intermediate band (IB) and further transferred to the conduction band (CB). This contributes to the quasi-Fermi-level split and hence enhances photocurrent of solar cells without degradation of voltage [ , , ].
What is the inverse of light-emitting diode structures based on QDs?
A variation of these configurations is to disperse the QDs into a blend of electron and hole-conducting polymers . This scheme is the inverse of light-emitting diode structures based on QDs,,,, .
Greatly, slowed hot electron cooling in InP QDs has been observed by the research group at NREL . For QDs, one mechanism for breaking the phonon bottleneck that is predicted to slow carrier cooling in QDs and hence allow fast cooling is an Auger process.