Ge/GaAs/InGaP Triple-Junction Solar Cells for

Space ExplorationSANAT PANDEY

ECE 443 TCAD Project

Outline

▪ Motivation

▪ Technical Background

▪ Design and Related Physics

▪ Simulation Results

▪ Conclusion

Outline

▪ Motivation

▪ Technical Background

▪ Design and Related Physics

▪ Simulation Results

▪ Conclusion

▪ Spacecrafts such as Europa Clipper rely on Solar Cells for

functionality

▪ Have strict weight limit to be met

▪ Reduce the number of Cells

▪ Generate same power

▪ Higher maneuverability

▪ Reduce cost of lifting a payload into space, manufacturing,

and assembly

Motivation

4

Outline

▪ Motivation

▪ Technical Background

▪ Design and Related Physics

▪ Simulation Results

▪ Conclusion

▪ 𝐼 𝑉 = 𝐼𝑜𝑝 − 𝐼0 𝑒𝑞 𝑉+𝐼𝑅𝑆

𝑘𝑇 − 1 −𝑉+𝐼𝑅𝑆

𝑅𝑠ℎ

▪ 𝐹𝑖𝑙𝑙 𝐹𝑎𝑐𝑡𝑜𝑟 𝐹𝐹 =𝑉𝑚𝑝𝐼𝑚𝑝

𝑉𝑜𝑐𝐼𝑠𝑐

▪ 𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 𝜂 =𝑉𝑜𝑐𝐼𝑠𝑐𝐹𝐹

𝑃𝑖𝑛, where Pin is

the input power

Technical Background

6

Equivalent Circuit [1]IV Curve and Output Power [1]

Photon Absorption Mechanism [1]

[1] Tao, Yuguo & Rohatgi, Ashish. “High‐Efficiency Front

Junction n‐Type Crystalline Silicon Solar Cells”, Intech

Open, http://dx.doi.org/10.5772/65023 (2017)

Triple Junction over single or

double junction Solar Cell to

reduce Thermalization

Design and Related Physics

7

Thermalization [2]

[2] K. E. Jasim, “Quantum Dot Solar Cells”,

Intech Open, http://dx.doi.org/10.5772/59159

(2018)

Wavelength Spectrum Covered [3]

[3] P. Michalopoulos, “A novel approach for the development and optimization of

state-of-the-art photovoltaic devices using Silvaco,” M.S. thesis, Dept. of Elec.

and Comp. Engr., Naval Postgraduate School, Monterey, CA, 2002.

Design and Related Physics Continued

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0

500

1000

1500

2000

2500

0 500 1000 1500 2000 2500

Inte

nsi

ty (

W/m

2)

Wavelength (nm)

Solar Irradiance Comparison of Earth and

Jupiter

Jupiter

Earth 𝐻 = 𝐻𝑠𝑢𝑛𝑅𝑠𝑢𝑛2

𝐷2

Solar Constant: Earth = 1353 W/m2

Jupiter = 50 W/m2

Intensity reduces by a factor of 27.06!!!

Solar Radiation In Space, https://pvcdrom.pveducation.org/SUNLIGHT/SPACE.HTM, Accessed on 2019-04-21

9

Simulation Results

10

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.00 0.50 1.00 1.50 2.00 2.50

Curr

ent

Den

sity

(m

A/c

m2)

Voltage (V)

JV Chracteristic for Model 1

Jsc= 0.613 mA/cm2

Voc ~ 2.3 V

FF= 89.24%

Efficiency= 25.394%

Simulation Results

11

Energy Band Diagram

Current Density Distribution

Cross-sectional Current

Relative energy density

12

Ge (m) GaAs (m)

InGaP (m)

Width (m)

TJ Doping Compared to model 1

Eff (%)

11 3.5 0.45 5 Model 1 25.39420 3.5 0.45 5 Same 25.62820 6.4 0.45 5 Same 25.63220 6.4 0.82 5 Same 24.16420 6.4 0.82 10 Same 23.98320 6.4 0.82 15 Same 24.03511 3.5 0.45 10 Same 25.22011 3.5 0.45 8 Same 22.95111 3.5 0.45 5 Double 25.46115 4.8 0.62 10 Double 24.95215 5 0.8 10 Double 25.23915 5 0.8 15 Double 25.29820 5 0.8 15 Double 25.40520 6.4 0.82 10 Double 23.985

▪ Drop in Intensity affects the efficiency more than predicted

▪ Modifying parameters to find an optimal point of high

efficiency for Ge/GaAs/InGaP triple junction cells

▪ Research in InGaN/GaN solar cells: vary the In and Ga

content in InGaN, we can get cover the whole solar

irradiance.

Conclusion

13

THANK YOU!

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