Efficient Lead-Free Perovskite Solar Cell · TABLE VI: Absorber characteristics for lead-free perovskite solar cells. Highlighted text are the characteristics that remained the same

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

6

▪ 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

12

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

13

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

14

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

15

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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