DocumentCode :
3512476
Title :
Decoupling spectral overlap of intermediate band solar cells using low-high state filling
Author :
Lin, Albert ; Phillips, Jamie
Author_Institution :
Inst. of Electron. Eng., Nat. Chiao-Tung Univ., Hsinchu, Taiwan
fYear :
2012
fDate :
3-8 June 2012
Abstract :
The high efficiency predicted for solar cells based on multi-photon processes relies on the assumption of optical transitions with non-overlapping spectral bands. Spectral overlap reduces the conversion efficiency due to energy loss associated with improper usage of higher energy photons for lower energy optical transitions. In this study, device structures with non-uniform occupation of intermediate electronic states are proposed to reduce the dependence of conversion efficiency on spectral overlap. Solar cell conversion efficiencies are calculated for structures where absorption bands are spatially decoupled due to defined occupation of intermediate states. Conversion efficiencies for a two section and three section device with spectral overlap of 4 eV are determined to be 52.8 % and 61.5 %, respectively, and are significantly larger than the calculated efficiency of 35.1% for the case of a standard multi-photon cell with uniform half-filled intermediate states The spectrally-decoupled device provides a means to achieve high theoretical efficiency independent of spectral overlap that approaches the detailed balance efficiency limit of 63.2 % for intermediate state devices without spectral overlap and 63.8 % for unconstrained triple-junction tandem cells.
Keywords :
multiphoton processes; solar cells; absorption bands; decoupling spectral overlap; device structures; electron volt energy 4 eV; energy optical transitions; energy photons; intermediate band solar cells; intermediate electronic states; intermediate state devices; low-high state filling; multiphoton processes; non-overlapping spectral bands; nonuniform occupation; solar cell conversion efficiencies; standard multiphoton cell; unconstrained triple-junction tandem cells; uniform half-filled intermediate states; Absorption; Electron optics; Filling; Hafnium; Photonics; Photovoltaic cells; Quantum dots; intermediate state/band; solar cell; spectral overlap; subbandgap photovoltaics;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Photovoltaic Specialists Conference (PVSC), 2012 38th IEEE
Conference_Location :
Austin, TX
ISSN :
0160-8371
Print_ISBN :
978-1-4673-0064-3
Type :
conf
DOI :
10.1109/PVSC.2012.6317571
Filename :
6317571
Link To Document :
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