Passivated Solar Cell Contacts With Zoned Poly-Si Capping

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Solution Overview

Problem

In crystalline silicon solar cells, the passivation of contacts is compromised due to damage from thermal curing of silver paste, leading to reduced conversion efficiency and increased parasitic light absorption, especially when polycrystalline silicon passivating contacts are applied on both sides of the cell.

Innovation Solution

A photovoltaic device structure featuring a silicon substrate with a first tunnel layer, a full-area or patterned first polycrystalline silicon-based capping layer, a second tunnel layer, and a second polycrystalline silicon-based capping layer applied only in predetermined zones, with metal contacts directly on the capping layer, keeping metal away from the substrate-tunnel layer interface to minimize damage and absorption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a relatively thick poly-Si capping layer is used to provide excellent passivation, then passivation quality is improved, but parasitic light absorption increases which reduces conversion efficiency

Engineering Contradiction:

Improvepassivation qualityVSAvoidparasitic light absorption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The device is divided into predetermined zones where the second poly-Si capping layer is applied only in specific areas rather than covering the entire surface. This segmentation allows passivation to be concentrated where needed (at contact regions) while leaving other areas free for light absorption, thus resolving the contradiction between passivation quality and parasitic light absorption.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The poly-Si capping layer is applied with spatially varying properties: thick poly-Si layers are placed only in predetermined zones where contacts are formed to provide local passivation, while other areas have no poly-Si capping layer to minimize light absorption. This local differentiation optimizes both passivation and optical performance.

Inventive Principle:

Principle #3Local quality

2Reliability

If poly-Si passivating contacts are applied on both sides of the solar cell to maximize photo-generation, then passivation is improved, but optical losses occur in UV, visible and infrared regions

Engineering Contradiction:

Improvepassivation levelVSAvoidoptical losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The poly-Si passivating contacts are segmented and applied only in predetermined zones rather than as full-surface layers. This allows the device to maintain high passivation levels at contact regions while minimizing optical losses in the active light-absorbing areas, addressing the contradiction between comprehensive passivation and optical transparency.

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If metal contacts are applied directly on the substrate to simplify manufacturing, then ease of manufacture is improved, but contact recombination increases reducing cell efficiency

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidcontact recombination

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

A tunnel layer is introduced as an intermediary between the metal contact and the silicon substrate. This tunnel layer acts as a mediator that enables electrical contact while providing passivation to reduce recombination losses, thus resolving the contradiction between manufacturing simplicity and contact recombination without requiring complex multi-layer structures.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration maximizes passivation and minimizes parasitic light absorption, enhancing cell efficiency, fill factor, open-source voltage, and short-circuit current by maintaining high passivation levels without excessive optical losses.

Implementation Method 1

a first tunnel layer situated upon at least a first side of said silicon substrate; a second tunnel layer situated upon substantially the entirety of said first polycrystalline silicon-based capping layer

Methodology Applied

Scientific EffectQuantum tunneling:

Implementation Method 2

crystalline silicon solar cells... conversion efficiency of light impinging on the cell into electrical current

Methodology Applied

Scientific EffectPhotovoltaic effect: Photovoltaic Effect

Data Source

PatentUS20240162354A1Photovoltaic device with passivated contact and corresponding method of manufacture

Publication Date: 2024.05.16 CSEM CENTRE SUISSE D ELECTRONIQUE ET DE MICROTECHNIQUE SA

AI summary

Disclosed is a photovoltaic device including: —a silicon substrate; —a first tunnel layer situated upon at least a first side of the silicon substrate; —a first polycrystalline silicon-based capping layer situated upon the first tunnel layer; and—a second tunnel layer situated upon substantially the entirety of the first polycrystalline silicon-based capping layer. The photovoltaic device further includes: —a second polycrystalline silicon-based capping layer situated upon predetermined zones of the second tunnel layer, areas of the second tunnel layer situated outside of the predetermined zones being free of the second polycrystalline silicon-based capping layer; and—a metal contact situated upon at least part of the second polycrystalline silicon-based capping layer.