Solar cells based on quantum dots:: Multiple exciton generation and intermediate bands

被引:168
作者
Luque, Antonio
Marti, Antonio
Nozik, Arthur J.
机构
关键词
D O I
10.1557/mrs2007.28
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Semiconductor quantum dots may be used in so-called third-generation solar cells that have the potential to greatly increase the photon conversion efficiency via two effects: (1) the production of multiple excitons from a single photon of sufficient energy and (2) the formation of intermediate bands in the bandgap that use sub-bandgap photons to form separable electron-hole pairs. This is possible because quantization of energy levels in quantum dots produces the following effects: enhanced Auger processes and Coulomb coupling between charge carriers; elimination of the requirement to conserve crystal momentum; slowed hot electron-hole pair (exciton) cooling; multiple exciton generation; and formation of minibands (delocalized electronic states) in quantum dot arrays. For exciton multiplication, very high quantum yields of 300-700% for exciton formation in PbSe, PbS, PbTe, and CdSe quantum dots have been reported at photon energies about 4-8 times the HOMO-LUMO transition energy (quantum dot bandgap), respectively, indicating the formation of 3-7 excitons/photon, depending upon the photon energy. For intermediate-band solar cells, quantum dots are used to create the intermediate bands from the confined electron states in the conduction band. By means of the intermediate band, it is possible to absorb below-bandgap energy photons. This is predicted to produce solar cells with enhanced photocurrent without voltage degradation.
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页码:236 / 241
页数:6
相关论文
共 51 条
[1]   HOT CARRIER INJECTION AT SEMICONDUCTOR-ELECTROLYTE JUNCTIONS [J].
BOUDREAUX, DS ;
WILLIAMS, F ;
NOZIK, AJ .
JOURNAL OF APPLIED PHYSICS, 1980, 51 (04) :2158-2163
[2]   THRESHOLDS OF IMPACT IONIZATION IN SEMICONDUCTORS [J].
BUDE, J ;
HESS, K .
JOURNAL OF APPLIED PHYSICS, 1992, 72 (08) :3554-3561
[3]   QUANTUM EFFICIENCY OF INTERNAL PHOTOELECTRIC EFFECT IN SILICON AND GERMANIUM [J].
CHRISTENSEN, O .
JOURNAL OF APPLIED PHYSICS, 1976, 47 (02) :689-695
[4]   Highly efficient multiple exciton generation in colloidal PbSe and PbS quantum dots [J].
Ellingson, RJ ;
Beard, MC ;
Johnson, JC ;
Yu, PR ;
Micic, OI ;
Nozik, AJ ;
Shabaev, A ;
Efros, AL .
NANO LETTERS, 2005, 5 (05) :865-871
[5]  
ELLINGSON RJ, 2004, P ECS M SAN ANT
[6]   Impact ionization can explain carrier multiplication in PbSe quantum dots [J].
Franceschetti, A. ;
An, J. M. ;
Zunger, A. .
NANO LETTERS, 2006, 6 (10) :2191-2195
[7]  
Grätzel M, 2000, PROG PHOTOVOLTAICS, V8, P171, DOI 10.1002/(SICI)1099-159X(200001/02)8:1<171::AID-PIP300>3.0.CO
[8]  
2-U
[9]   Charge separation and transport in conjugated-polymer/semiconductor-nanocrystal composites studied by photoluminescence quenching and photoconductivity [J].
Greenham, NC ;
Peng, XG ;
Alivisatos, AP .
PHYSICAL REVIEW B, 1996, 54 (24) :17628-17637
[10]  
Greenham NC, 1997, AIP CONF PROC, P295, DOI 10.1063/1.53475