25-07-2013 дата публикации
Номер: US20130186458A1
A design of a quantum well region that allows faster and more efficient carrier collection in quantum well solar cells. It is shown that for a quantum well material system displaying a negligible valence band offset, the conduction band confinement energies and barrier thicknesses can be designed to favor a sequential thermionic promotion and resonant tunneling of electrons to the conduction band continuum resulting in faster carrier collection rates than for a conventional design. An evaluation of the proposed design in the context of devices incorporating GaAs/GaAsN quantum wells shows a collection of all photo-generated carriers within several to tenths of ps (10s) from deep quantum wells rather than several ns, as it is the case for conventional designs. The incorporation of the proposed design in single and multijunction solar cells is evaluated with efficiency enhancements. 1. A multi-quantum well solar cell comprising:two or more subcells incorporated into the intrinsic region of a GaAs p-i-n solar cell;wherein each subcell comprises at least a first quantum well and a second quantum well; andwherein the first quantum well and the second quantum well are resonantly coupled.2. The multi-quantum well solar cell of claim 1 , wherein the energy levels of the quantum wells are optimized to facilitate electronic escape using both thermoionic and quantum tunneling.3. The multi-quantum well solar cell of claim 1 , wherein the conversion efficiency of the solar cell is in excess of 35% at AM0.4. The multi-quantum well solar cell of claim 1 , wherein collection of photo-generated carriers occurs within 0.1 to 10 ps.5. A multi-quantum well solar cell comprising: [{'sub': 0.982', '0.018', '0.982', '0.018', '0.982', '0.018, 'wherein each subcell comprises a first quantum well consisting of 30 monolayers of GaAsN, a second quantum well consisting of 12 monolayers of GaAsN, and a third quantum well consisting of 3 monolayers of GaAsN;'}, 'wherein the first quantum well is ...
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