# Simulation of Thin-Film Solar Cells

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```					Simulation Requirement   Calculation Method   Structure   Oblique Incident Light   Results   Outlook

Simulation of Thin-Film Solar Cells

Dipl.-Technomath. Christine Jandl

Department of Computer Science 10 (LSS)
University of Erlangen-Nuremberg

18. November 2009

HZB 18.11.2009                                                                               C. Jandl
Simulation Requirement   Calculation Method   Structure   Oblique Incident Light   Results   Outlook

Outline

1 Simulation Requirement

2 Calculation Method

3 Structure

4 Oblique Incident Light

5 Results

6 Outlook

HZB 18.11.2009                                                                               C. Jandl
Simulation Requirement   Calculation Method   Structure   Oblique Incident Light   Results   Outlook

Simulation Requirement

• Solve Maxwell’s equations
ˆ
iω E = 1           ˆ
× H − σEˆ
ˆ     1         ˆ   σ∗ ˆ
iω H = − µ       ×E − µ H
abs,λ         P
• Calculate quantum eﬃciency QE (λ) := P
in,λ

• Calculate short-circuit current density
JSC =               AM1.5 ∆λ eλ
λ QE (λ)Pλ        hc

HZB 18.11.2009                                                                               C. Jandl
Simulation Requirement   Calculation Method   Structure     Oblique Incident Light   Results   Outlook

Calculation Method

• Finite Integration Technique (FIT)
• Staggered grid → periodic boundary conditions

1D staggered grid                               3D staggered grid

HZB 18.11.2009                                                                                 C. Jandl
Simulation Requirement        Calculation Method     Structure     Oblique Incident Light   Results   Outlook

Structure

3D - Simulation of Diﬀerent Structures
• Flat, rectangular, pyramidal
• Integration of AFM scans

structure of a solar cell               AFM scan by Fraunhofer
IST Braunschweig

HZB 18.11.2009                                                                                        C. Jandl
Simulation Requirement   Calculation Method   Structure   Oblique Incident Light   Results   Outlook

Structure

Discretization
• Size of the computational domain: 2.5µm × 2.5µm × 2.4µm
• Number of points depend on wavelength
(λ = 550nm, ..., 1000nm): between 6 and 50 million points
→ High Performance Computing

HZB 18.11.2009                                                                               C. Jandl
Simulation Requirement   Calculation Method   Structure   Oblique Incident Light   Results   Outlook

Structure

AFM Scan
• Original size: 5µm × 5µm
• Mirrored due to periodicity
→ computational domain: 10µm × 10µm
→ too large computational domain!

HZB 18.11.2009                                                                               C. Jandl
Simulation Requirement    Calculation Method   Structure   Oblique Incident Light   Results   Outlook

Structure

AFM Scan
• Size of random part of scan 1.2µm × 1.2µm
• Mirrowed part → new simulation domain: 2.4µm × 2.4µm

original scan                             simulated scan

HZB 18.11.2009                                                                                C. Jandl
Simulation Requirement   Calculation Method   Structure   Oblique Incident Light   Results   Outlook

Oblique Incident Light

Until Now:                                          New:
using periodic extension                            using phase shift

HZB 18.11.2009                                                                               C. Jandl
Simulation Requirement      Calculation Method   Structure   Oblique Incident Light   Results   Outlook

Oblique Incident Light

Comparison: Simulation vs. Experiment
Quantum eﬃciency of a ﬂat structured solar cell for diﬀerent
incident angles α

2D simulation                           experimental data

HZB 18.11.2009                                                                                  C. Jandl
Simulation Requirement   Calculation Method   Structure   Oblique Incident Light   Results   Outlook

Results

Simulation Data
• Simulation with integrated AFM scan
• Size of simulation domain: 2.4µm × 2.4µm × 2.38µm
• Wavelength range: 550nm − 995nm
• Distance: ∆λ = 5nm
• Number of points: between 6 (995nm) and 46 millions (550nm)
• Number of MPI processors: 1000
• Average duration: 4 - 5 hours

HZB 18.11.2009                                                                               C. Jandl
Simulation Requirement   Calculation Method   Structure       Oblique Incident Light    Results       Outlook

Results

Quantum Eﬃciency                                    Short-Circuit Current Density
Rand01    Rand02     Rand03
diﬀerent random domains per                                 h
JSC mA/cm2
i
8.982    9.242      9.125
wavelength
→ max derivation: 2.9%

HZB 18.11.2009                                                                                        C. Jandl
Simulation Requirement      Calculation Method   Structure   Oblique Incident Light   Results   Outlook

Results

3D structure                            |E |2 (λ = 800nm)

HZB 18.11.2009                                                                                  C. Jandl
Simulation Requirement   Calculation Method   Structure   Oblique Incident Light   Results   Outlook

Outlook

Future Projects

• Integration of silver nanoparticle
• New implementation for oblique incident waves
• Less memory capacity and computing time
• Smaller wavelengths (start at 350nm)
• Larger computational domain
• Tandem solar cell (with integrated AFM scan)

HZB 18.11.2009                                                                               C. Jandl
Simulation Requirement   Calculation Method   Structure   Oblique Incident Light   Results   Outlook

Outlook

Tandem Solar Cell
Size of the computational
domain:
2.5µm × 2.5µm × 3.55µm

HZB 18.11.2009                                                                               C. Jandl

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