Solar Cell Design Madeline Oglesby Kang Kang Kyle Veugeler Jay - - PowerPoint PPT Presentation

Solar Cell Design

Madeline Oglesby Kang Kang Kyle Veugeler Jay Eggenberger Dan Congreve

Spectrum Splitting Overview

• Spectrum Splitting

▫ Different materials in p-i-n junctions have unique optical properties ▫ Use two or more layers with different optical properties

 This can maximize the range of absorbed wavelengths

• Tandem Junction Solar Cell

▫ A solar cell with two of these layers

• Current Matching

▫ Layers are connected in series ▫ Current through each layer must be the same ▫ Effective current of both layers is limited by the layer with the lowest current.

Current Matching Equations

• Carrier Calculation for a-Si layer:
• Carrier Calculation for nc-Si layer:
• Current Matching Equation (yields ratio of ta-Si to tnc-Si):

=

Anti-Reflective Coating

Definition

• Layer of transparent conductive oxide
• Serves as the top contact for the solar cell

Goals

• Minimize absorption and reflection losses for

incident light of wavelengths 400-1100 nm

• Provide good electrical contact while letting most of

the incident light pass through to the a-Si and nc-Si layers where the photo-generation of current occurs

Solar Cell Optics Simulator

ARC Metric

• Red line: Average reflection
• ver 400-1100 nm range
• Blue line: Average absorption

in ARC

• Black line: Sum of reflection

and ARC absorption (loss)

• Optimal case is minimum of

black line

Current Findings

ARC Material Optimal Thickness Light R+A Bare Layer No ARC 0 nm 56.14% ITO (Layer 1) 67 nm 44.73% SnO2(Layer 1) 69 nm 41.62% SnO2/ITO Mix(Layer 1) 78 nm 42.55% ZnO 67 nm 41.83% (ITO/SnO2)/ZnO 32nm(ITO) 45nm(ZnO) 41.14% (ITO/SnO2)/ITO 39nm(ITO/SnO2) 40nm (ITO) 41.83%

Implementation Process

Determine Design Fabricate Cell Test Cell Analyze Results

Testing Procedures

• Quantum Efficiency

▫ Carriers Collected/Carriers Absorbed at a specific wavelength ▫ Shows potential flaws in the device

• I-V Curve

▫ Taken at various temperatures ▫ Shows how the device will operate in real world conditions

Testing Procedures

• C-V Curve

▫ Act as design verification and guide ▫ Calculate physical thickness of the device

• Optical Properties

▫ Measure Reflection & Transmission ▫ Study the effectiveness of ARC ▫ Determine physical thickness