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Advanced Characterization of Intermediate Band Solar Cells Intermediate Band Solar Cells Antonio Luque, A Mart Instituto de Energ a Solar Instituto de Energ a Solar Universidad Polit cnica de Madrid Spain Japan Joint Workshop on

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SLIDE 1

Advanced Characterization of Intermediate Band Solar Cells Intermediate Band Solar Cells

Antonio Luque, A Martí Instituto de Energía Solar Instituto de Energía Solar Universidad Politécnica de Madrid

Spain Japan Joint Workshop on Spain-Japan Joint Workshop on

Nanoscience and New Materials

“Ari s” 37th Fl r ANA Int rc ntin nt l T k Aries”, 37th Floor, ANA Intercontinental Tokyo April 20, 2009, Tokyo, Japan

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SLIDE 2

Contents I d i

  • Introduction
  • QD implementation

C h

  • Current enhancement
  • Voltage preservation
  • High flux operation
  • Some characterisation Instruments

Some characterisation Instruments

  • Conclusions
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SLIDE 3

Contents I d i

  • Introduction
  • QD implementation

C h

  • Current enhancement
  • Voltage preservation
  • High flux operation
  • Some characterisation Instruments

Some characterisation Instruments

  • Conclusions
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SLIDE 4

Photocurrent gain

  • A. Luque y A. Martí, Phys. Rev. Lett. 78(26) 5014–5017 (1997).
  • A. Luque and A. Martí, Prog. in Photov, Res. and Appl. 9(2) 73–86 (2001).
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SLIDE 5

Voltage preservation

V

  • A. Luque y A. Martí, Phys. Rev. Lett. 78(26) 5014–5017 (1997).
  • A. Luque and A. Martí, Prog. in Photov, Res. and Appl. 9(2) 73–86 (2001).
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SLIDE 6

Optimum gaps

  • A. Luque & A. Martí, Phys.

Rev Lett 78 5014 (1997) 63.2 %

  • Rev. Lett. 78 5014 (1997)

0,71 eV 1,24 eV 1,95 eV W Shockley & HJ Queisser, y Q ,

  • J. Appl. Phys. 32 510 (1961)
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SLIDE 7

Two-photon mechanism necessary

  • A. Luque, A. Martí, and L. Cuadra, Physica E 14, 107 (2002).
  • A. Luque, A. Martí, C. Stanley, et al., Journal of Applied Physics 96, 903 (2004).
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SLIDE 8

IBSC & Tandems

tandem of 2 IBSC: conventional 6 gaps tandem tandem of 2 IBSC: 6 gaps only one tunnel junction g p 5 tunnel junctions

  • E. Antolín, A. Martí, and A. Luque, in Proc. of the 21st European Photovoltaic Energy Conference, 2006,
  • pp. 412--415.
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SLIDE 9

Some proven IB bulk materials

  • Zn0.88Mn0.12Te0.987O0.013 detected by photo-

fl t reflectance

–

  • K. M. Yu et al., Physical Review Letters 91, 246403 (2003)
  • GaN As1

P alloys with y>0 3 detected by photo-

  • GaNxAs1−x−yPy alloys with y>0.3 detected by photo-

reflectance

– K. M. Yu et al., Applied Physics Letters 88, 092110 (2006)

  • V0.25In1.75S3 detected by absorption coefficient

– R. Lucena et al., Chem. Mat. 20, 5125 (2008) P Palacios et al Phys Rev Lett 101 046403 (2008) – P. Palacios et al., Phys. Rev. Lett. 101, 046403 (2008)

  • Si:Ti (∼0.2%) detected by Hall experiments

– G. Gonzalez-Díaz et al., Submitted for publication (2009) , p ( )

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SLIDE 10

Contents I d i

  • Introduction
  • QD implementation

C h

  • Current enhancement
  • Voltage preservation
  • High flux operation
  • Some characterisation Instruments

Some characterisation Instruments

  • Conclusions
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SLIDE 11

Quantum dots for the IBSC

  • A. Martí, L. Cuadra, and A. Luque, in Proc. of the 28th IEEE Photovoltaics Specialists Conference, edited

by IEEE (New York, 2000).

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SLIDE 12

QD-IBSC

  • A. Martí, L. Cuadra, and A. Luque, in Proc. of the 28th IEEE Photovoltaics Specialists Conference, edited

by IEEE (New York, 2000).

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SLIDE 13

Structures grown

In collaboration with: University of Glasgow University of Glasgow

Grown in MBE, in Stranski-Krastanov mode

  • A. Luque, A. Martí, C. Stanley, N. López, L. Cuadra, D. Zhou y A. Mc-Kee, J. Appl. Phys. 96(1) 903, 2004.
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SLIDE 14

GSRH Modelling the QD-IBSC

h

τ OC

e

τ

Hole lifetime (ps) 40.0 Hole lifetime (ps), 40.0 Electron lifetime (ps), 0.5

  • A. Luque, A. Martí, N. López, et al., Journal of Applied Physics 99, 094503, (2006)
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SLIDE 15

Contents I d i

  • Introduction
  • QD implementation

C h

  • Current enhancement
  • Voltage preservation
  • High flux operation
  • Some characterisation Instruments

Some characterisation Instruments

  • Conclusions
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SLIDE 16

Strain destroys the emitter

In collaboration with: University of Glasgow

  • A. Marti et al., Applied Physics Letters 90, 233510 (2007)
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SLIDE 17

Better results with strain compensated QD

  • S. M. Hubbard, C. D. Cress, C. G. Bailey, R. P. Raffaelle, S. G. Bailey, and D. M. Wilt, APL 92 (2008)
  • S. M. Hubbard, C. G. Bailey, C. D. Cress, et al. Short circuit current enhancement… 33st IEEE PVSC, 2008
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SLIDE 18

High current no voltage reduction!

Confidential: Unpublished material Y. Okada, Japan-EU collaboration workshop. See also R. Oshima, A. Takata, and Y. Okada, Applied Physics Letters 93, 083111 (2008)

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SLIDE 19

8JV C <

Preliminary GSRH modeling of Tokyo University IB cells

0.005 0.010

8JV-Curve<

250 300 350

8Wide, 0.3<

0.0 0.5 1.0 E

8Wide, 0.3<

0 005 0.000 JêAcm-2

100 150 200 qGêAcm-3

0.00001 0.00002 0.00003 0.00004

  • 1.0
  • 0.5

xêcm

0.0 0.2 0.4 0.6 0.8 1.0

  • 0.010
  • 0.005

VêV

0.00001 0.00002 0.00003 0.00004 50 xêcm

VêV 0.025 0.030

8JV-Curve<

  • Effect of the GaNAs not considered
  • Very high density of confined levels (∼1018 cm-

3); large IB region (400 nm) ê

0.010 0.015 0.020 JêAcm-2

  • Generation does not extend trough the IB

region because of good isolation with CB (σn~3*10-16 cm-2). Go to IB doping? Model first!

  • Excellent low-recombination sub-bandgap cells

σn = 3 ê10^ 16; σp = 3 ê10 ^19; vth = 10^7; Nt = 1 ∗10^ 18; Nc = 4.7 ∗10^ 17; Nv = 7 ∗10 ^18; T = 300; ND = 0 ∗10 ^17; kT = T ∗ BoltzmannConstant ∗ Kelvin êJoule ê ElectronCharge ∗ Coulomb; Ev = 0; Ec = 1.41; Et = 1.13; W = 0.00004; Epsilon = 12; pp = 10^ 18; nn = 5 ∗ 10^17; Jpl = 0.015; Jnl = 0.015; γpl = Jpl êHElectronCharge ê CoulombLê W êvth ê Nt γnl = Jnl êHElectronCharge êCoulombLê W ê vth ê Nt

0.0 0.2 0.4 0.6 0.8 1.0 0.000 0.005

Excellent low recombination sub bandgap cells (σp<3*10-17 cm-2)

  • No loss of voltage because bulk cell is too poor

H g L Jcvl = 0.01971; Vcvoc = 0.84;

VêV

Confidential: unpublished material: A. Luque

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SLIDE 20

Contents I d i

  • Introduction
  • QD implementation

C h

  • Current enhancement
  • Voltage preservation
  • High flux operation
  • Some characterisation Instruments

Some characterisation Instruments

  • Conclusions
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SLIDE 21

Band shrinkage

  • A. Luque, A. Martí, C. Stanley, N. López, L. Cuadra, D. Zhou y A. Mc-Kee, J. Appl. Phys. 96(1) 903, 2004.
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SLIDE 22

Are we making QDs or QWs?

0 2 0.0

  • 0.6
  • 0.4
  • 0.2

1 2

  • 1.0
  • 0.8
  • 2. μ10-9
  • 4. μ10-9

6.μ10-9

  • 8. μ10-9

1.μ 10-8

  • 1.4
  • 1.2

Energy levels in a spherical potential well with s, p, d, f angular symmetry , p, , g y y

  • vs. the well radius (colours principal

quantum number; line structure, angular symmetry). Confidential: unpublished material: A. Luque

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SLIDE 23

QD level structure:

Comparing photo-reflectance and electroluminescence

In collaboration with: University of Glasgow

  • E. Cánovas, A. Martí, N. López, E. Antolín, P. G. Linares, C. D. Farmer, C. R. Stanley, and A. Luque, Thin

Solid Films 516, 6943 (2008).

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SLIDE 24

QD level structure:

Comparing photo-reflectance and quantum calculations

  • E. Cánovas, A. Martí, N. López, et al, Thin Solid Films 516, 6943 (2008).
  • V. Popescu, G. Bester, M. C. Hanna, A. G. Norman, and A. Zunger, Physical Review B 78, 205321 (2008).
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SLIDE 25

Contents I d i

  • Introduction
  • QD implementation

C h

  • Current enhancement
  • Voltage preservation
  • High flux operation
  • Some characterisation Instruments

Some characterisation Instruments

  • Conclusions
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SLIDE 26

DB modeling; the effect of concentration

30 2% 30.2% 31.0%

Impossible to

51.6% 36.7%

exceed ordinary cells!!!

(at one sun with (at one sun with GaAs/InAs)

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SLIDE 27

IES experience in concentrator cells

Best concentrator III-V solar cells (certified efficiencies)

40 45

3J LMM (FhG-ISE) 3J LMM (S t l b)

  • C. Algora &
  • E. Barrigón

( G S )

35 ncy (%)

2J LM GaInP/GaAs (IES-UPM) 3J IM-LMM (NREL) 3J LMM (Spectrolab) 3J LMM (FhG-ISE)

30 Efficien

( ) 2J LMM GaInP/GaInAs (FhG-ISE)

20 25

1J GaAs (IES-UPM)

20 1 10 100 1000 10000 Concentration, X (suns)

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SLIDE 28

DB modeling; the effect of concentration

1000 suns reference level

  • A. Martí, E. Antolín, E. Cánovas, N. López, P. G. Linares, A. Luque, C. R. Stanley, and C. D. Farmer, Thin

Solid Films, p. doi: 10.1016/j.tsf.2007.12.064, 2008.

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SLIDE 29

Concentration measurements at room temperature

GaAs reference GaAs reference

Confidential: unpublished material: P. García Linares E. Antolín and A. Martí

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SLIDE 30

Concentration measurements at 20 K

GaAs reference GaAs reference

Confidential: unpublished material: P. García Linares E. Antolín and A. Martí

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SLIDE 31

Contents I d i

  • Introduction
  • QD implementation

C h

  • Current enhancement
  • Voltage preservation
  • High flux operation
  • Capabilities for this cooperation

Capabilities for this cooperation

  • Conclusions
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SLIDE 32

Concentrator cell capability at IES/UPM for this cooperation

  • High concentration cell processing on multilayer

epitaxied substrates epitaxied substrates

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SLIDE 33

Modeling & characterization techniques at IES/UPM for this cooperation

  • DB Modeling
  • GSRH Modeling
  • Photo/thermo/piezo-reflectance
  • Photo/electroluminescence down to 4K up to 8

microns

  • Photon counting down to 4K up to 8 microns
  • FTIR
  • DLTR
  • Quantum efficiency down to 4K up to 8 microns up to

10000 10000 suns

  • IV measurements down to 4K up to 10000 suns
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SLIDE 34

Conclusions

  • IBSC is an attractive promising new concept that can

be implemented with QDs be implemented with QDs

  • Promising results in getting higher current

Better understanding of the voltage loss

  • Better understanding of the voltage loss
  • Better understanding of the role of high flux light

I t t t f IBSC h i J Skill

  • Important support for IBSC research in Japan. Skills

for very high density QDs.

  • Modeling and characterization of IBSC and
  • Modeling and characterization of IBSC and

concentrator cell manufacturing skills in Spain

  • Cooperation can speed-up results
  • Cooperation can speed-up results.