Efficient Lead-Free Perovskite Solar Cell Bryce Smith ECE 498CB Term Project April 22, 2018
Efficient Lead-Free Perovskite Solar CellBryce SmithECE 498CB Term Project
April 22, 2018
▪ Motivation
▪ Technical Background
▪ Simulation Results
▪ Conclusions
Outline
▪ 28% Increase Energy Consumption
– Greenhouse Gasses
▪ Utility-Scale Solar Cost: 30% Decrease
– Lower PV Module & Inverter Costs
– Lower Labor Costs
– Higher Module Efficiency
Motivation
3L., Doman “U.S. Energy Information Administration - EIA - Independent Statistics and Analysis.” (2017)R. Fu, “U.S. Solar Photovoltaic System Cost Benchmark: Q1 2017.” (2017)
Why Perovskite Solar Cells?
4"NREL efficiency chart" https://www.nrel.gov/pv/assets/images/efficiency-chart.png
▪ Silicon Dominates 94% of Market
– Other 6% is Thin-Films
▪ Lower Production Costs
– Spin Coating
– Blade Spreading
Perovskite Solar Cells Vs. Market
5
TABLE I: Comparison of commercial solar cell record
efficiencies as of July 2017
Material Efficiency
Multi-Crystalline Silicon 26.7%
Single-Crystalline Silicon 21.9%
CdTe 21%
CIGS 21.7%
Perovskite 22.7%
“Photovoltaics Report.” Fraunhofer Institute for solar Energy Systems, ISE. (26 February 2018).
▪ High Efficiency Cells Made with Lead
– High Toxicity
– Environmental Impact
▪ Stability
– Lifetime of Cell
– Efficiency
▪ Lead-Free Perovskite a Solution?
– Goal: Efficiency of 10%
– Measured Efficiency:~3%
Problems with Perovskite Solar Cells
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▪ Motivation
▪ Technical Background
▪ Simulation Results
▪ Conclusions
Outline
▪ Generic Form: ABX3
– A = Organic Cation
– B = Inorganic Cation
– X3= Halogen Anion
Perovskite Structure
8
TABLE II: Possible Materials used in
Perovskite Structures9
A B C
Methylammonium
(CH3NH3)
Pb I
Formamidinum
(H2NCHNH2)
Sn Br
Cs Ti Cl
CH(CH3) BiAg -
Kamat, Prashant V., et al. “Lead-Free Perovskite Solar Cells.” ACS Energy Letters, vol. 2, no. 4, 14 Apr. 2017, pp. 904–905., doi:10.1021/acsenergylett.7b00246. Ossila. “Perovskites and Perovsktie Solar Cells: An Introduction” (2018)
▪ J-V Curve
▪ Important Parameters:
– JSC
– VOC
– PMAX (VM & IM)
– FF
– n
Solar Cell Performance
9Wei, James, and Antonio Braga. “Measuring the I-V Characteristic of PN Junction Devices with HF2LI Lock-in Amplifier.” Blog of James Wei, 13 May 2015,
▪ Motivation
▪ Technical Background
▪ Simulation Results
▪ Conclusions
Outline
▪ Copper Indium Gallium Selenide (CIGS)
– Similar Device Structure – Thin Films
– Wannier-type exciton
Developing a Baseline – Experimental Structure
11
TABLE III: Simulation parameters of perovskite solar cell in the study by
Minemoto and Murata11
Parameters SnO2:F
(TCO)
TiO2
(buffer)
IDL1
(defect
layer)
CH3NH3PbI
3-xClx(absorber)
IDL2
(defect
layer)
Spiro-
OMeTA
D (HTM)
Thickness (nm) 500 50 10 350 10 350
NA (cm-3) - - - - - 2x1018
ND (cm-3) 2x1019 1016 1013 1013 1013 -
𝜺𝒓 9.0 9.0 6.5 6.5 6.5 3.0
𝑿 (𝒆𝑽) (Affinity) 4.0 3.9 3.9 3.9 3.9 2.45
Eg (eV) 3.5 3.2 1.55 1.55 1.55 3.0
𝝁𝒏𝝁𝒑
(𝒄𝒎𝟐
𝑽𝒔)
20/10 20/10 2.0/2.0 2.0/2.0 2.0/2.0 2x10-
4/2x10-4
Nt (cm-3) 1015 1015 1017 2.5x1013 1017 1015
Minemoto, Takashi, and Masashi Murata. “Device Modeling of Perovskite Solar Cells Based on Structural Similarity with Thin Film Inorganic Semiconductor Solar Cells.” Journal of Applied Physics, vol. 116, no. 5, 2014
Simulated Structure
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TABLE IV: Final simulation parameters of lead-based
perovskite solar cell within the Crosslight software.
Parameters SnO2:F
(TCO)
TiO2
(buffer)
IDL1
(defect
layer)
CH3NH3
PbI3-xClx(absorbe
r)
IDL2
(defe
ct
layer)
Spiro-
OMeT
AD
(HTM)
Thickness
(nm)
250 100 5 165 5 175
NA (cm-3) - - - - - 2x1019
ND (cm-3) 2x1019 1019 1014 1014 1014 -
Comparison of Results
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TABLE V: Simulation results of lead-based perovskite from
Crosslight software
Parameter Value
Efficiency 9.75 %
ISC 10.43 mA/cm2
VOC 1.07 V
VM .9482 V
IM 9.909 mA/cm2
FF 58.7 %
Minemoto, Takashi, and Masashi Murata. “Device Modeling of Perovskite Solar Cells Based on Structural Similarity with Thin Film Inorganic Semiconductor Solar Cells.” Journal of Applied Physics, vol. 116, no. 5, 2014
Absorber Parameters
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TABLE VI: Absorber characteristics for lead-free perovskite solar cells. Highlighted text are the
characteristics that remained the same from the lead-based perovskite solar cell baseline
simulation
Material Eg (eV)18,20,21
𝜺𝒓19 m*
e19,20 m*
h19,20 𝝁𝒏
𝝁𝒑(𝒄𝒎𝟐
𝑽𝒔)19 𝑿 (𝒆𝑽)
(Affinity)18
CsSnBr3 1.75 32.4 0.084 0.082 2.0/2.0 4.6
CsSnI3 1.27 48.2 0.09 0.069 2.0/585 3.62
CsSnCl3 1.52 29.4 0.09 0.14 2.0/2.0 3.9
Cs2BiAgCl6 2.7 6.5 0.34 0.31 2.0/2.0 3.9
Cs2BiAgBr6 2.3 6.5 0.28 0.21 2.0/2.0 3.9
Cs2BiAgI6 1.6 6.5 0.13 0.19 2.0/2.0 3.9
Cs2TiBr6 1.8 6.5 0.09 0.71 2.0/2.0 3.9
Cs2TiI6 1.65 6.5 0.09 0.71 2.0/2.0 3.9
Cs2TiCl6 3.4 6.5 0.09 0.71 2.0/2.0 3.9
Simulation Results
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TABLE VII: Simulation results for lead-free perovskite solar cells.
Material Efficiency ISC
(mA/cm2)
VOC (V) VM (V) IM(mA/cm
2)
𝑭𝑭
CsSnBr3 8.8 % 8.84 1.33 1.03 8.29 72.6 %
CsSnI3 8.5 % 13.18 .995 .735 11.18 62.6 %
CsSnCl3 14.12 % 13.34 1.23 1.09 12.46 82.77 %
Cs2BiAgCl6 4.65 % 2.899 2.2 1.61 2.78 95.9 %
Cs2BiAgBr6 9.76 % 5.98 1.84 1.64 5.74 85.6 %
Cs2BiAgI6 15.9 % 16.2 1.18 1.01 15.18 80.2 %
Cs2TiBr6 12.1 % 10.8 1.3 1.15 10.14 83.1 %
Cs2TiI6 12.5 % 12.8 1.2 1.01 11.98 78.8 %
Cs2TiCl6 .68 % .45 1.9 1.57 .42 77%
▪ Simulations indicate efficiencies above 10% for Lead-Free
Perovskite Solar Cells
– Missing Optical Properties
– Missing Defects
– Oxidation of Inorganic Cation – Stability
– Need Better Understanding Before Optimization Can Occur
Conclusions
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