「 quantum dot solar cells 」 a. j. nozik, physica e 14 (2002) 115-120. yoshida lab. hiroaki...
TRANSCRIPT
contentscontents
Introduction Necessity of Quantum dot solar cells
Ways to increase conversion efficiency
Proposals of Quantum dot solar cell configuration
Summary
Present source of energy supply
Present source of energy supply
Environmental pollution
Environmental pollution
Eco-friendly new energyEco-friendly new energy
Solar energy generationSolar energy generation
BAD!!BAD!!
Introduction Necessity of Quantum dot solar cellsIntroduction Necessity of Quantum dot solar cells
Conversion efficiency of current solar cellsConversion efficiency of current solar cells
About 20%
About 20%
currentlycurrently
About 31%
About 31%
Theoretical limitTheoretical limit
Technical progressTechnical progress
Current solar cells can't cover the demand of energy on earthCurrent solar cells can't cover the demand of energy on earth
Quantum Dot (it is a semiconductor whose excitons are confined in all three spatial dimensions)
bulk Quantum dot
Discretization of energy level
Discretization of energy level
Present source of energy supply
Present source of energy supply
Environmental pollution
Environmental pollution
Eco-friendly new energyEco-friendly new energy
Solar energy generationSolar energy generation
BAD!!BAD!!
Introduction Necessity of Quantum dot solar cellsIntroduction Necessity of Quantum dot solar cells
Conversion efficiency of current solar cellsConversion efficiency of current solar cells
About 20%
About 20%
currentlycurrently
About 31%
About 31%
Theoretical limitTheoretical limit
Technical progressTechnical progress
Current solar cells can't cover the demand of energy on earthCurrent solar cells can't cover the demand of energy on earth
Quantum Dot (it is a semiconductor whose excitons are confined in all three spatial dimensions)
bulk Quantum dot
Discretization of energy level
Discretization of energy level
WW = = × × Higher photovoltages :V
or
Higher photocurrents :I
Way to increase conversion efficiency Way to increase conversion efficiency
VV II W:wattV :voltageI :current
Quantum dot
Function of quantum dot for the solar cellsHigher photovoltages from “discretization”
e
h
e
h
V 2
V1 < V 2
Higher photovoltages
V1
Bulk
Ec: bottom of conducton band
Ev: top of valence band
Function of quantum dot for the solar cellsHigher photocurrents from “Impact ionization”
Higher photocurrents
Function of quantum dot for the solar cellsHigher photovoltages from “Separation”
normalnormal
Separation!!Separation!!
Higher photocurrents
balk Quantum dot