Understanding the operation of quantum dot intermediate band solar cells

Abstract

Surface-plasmon enhanced absorption in organic solar cells by employing a periodically corrugated metallic electrode Appl. Phys. Lett. 101, 163303 (2012) Surface-plasmon enhanced absorption in organic solar cells by employing a periodically corrugated metallic electrode APL: Org. Electron. Photonics 5, 234 (2012) Development of pulsed laser deposition for CdS/CdTe thin film solar cells Appl. Phys. Lett. 101, 153903 (2012) Technology-compatible hot carrier solar cell with energy selective hot carrier absorber and carrier-selective contacts Appl. Phys. Lett. 101, 153901 (2012) Additional information on J. Appl. Phys. In this paper, a model for intermediate band solar cells is built based on the generally understood physical concepts ruling semiconductor device operation, with special emphasis on the behavior at low temperature. The model is compared to J L -V OC measurements at concentrations up to about 1000 suns and at temperatures down to 20 K, as well as measurements of the radiative recombination obtained from electroluminescence. The agreement is reasonable. It is found that the main reason for the reduction of open circuit voltage is an operational reduction of the bandgap, but this effect disappears at high concentrations or at low temperatures.

The effect of photonic bandgap materials on the Shockley-Queisser limit

“…In order to surpass this limit, one must consider the assumptions that are made and find systems that violate these assumptions. Such schemes are sometimes referred to as third generation photovoltaics 7 and are usually aimed at reducing thermalization losses through hot carrier collection, 8 multiexciton generation, [9][10][11] intermediate band collection, [12][13][14] or by channeling photons into absorbing layers whose bandgap energies are more closely matched to the incident photon energies, e.g., spectrum splitting or tandem multijunction solar cells. [15][16][17][18][19][20][21][22] Other techniques aim to circumvent this limit by exploiting various aspects of the derivation, which do not violate the overall assumptions of detailed balance; for instance, the use of angularly or spectrally selective filters, 3,23-26 which have found uses in intermediate band concepts 26 and multijunction designs.…”

Realistic performance prediction in nanostructured solar cells as a function of nanostructure dimensionality and density

“…At room temperature they provide a ladder for the electrons from and to the IB. 23 Furthermore, beyond 56 meV, population inversion will take place between the conduction and the highest confined level so producing an additional effective path to keep the IB and the CB at the same quasi Fermi level. Smaller QDs and a larger material bandgap are necessary to avoid this important drawback.…”

“…This simple law is frequently obeyed in n-type material under low injection conditions and will be supposed to hold in all the cases in this paper, without distinction as to whether the recombining electrons are in confined or extended states. 23 The lifetime is related to one or several defects that act as recombination centers by introducing deep levels. These traps are present even in nonstructured semiconductors but strain relaxation in InAs/GaAs nanostructures can produce them; in these paper, however, we assume the lifetime to be independent on the density of nano-sized features.…”

Realistic Detailed Balance Study of the Quantum Efficiency of Quantum Dot Solar Cells

“…Close to the operating voltage, non-radiative processes such as Shockley-Read-Hall (SRH) recombination become important. [ 16 ] However, SRH can be minimized by improving material quality. Results of the model at operating voltage therefore correspond to the best that be achieved by a proposed QD-IBSC.…”