Back-Contact Solar Cell Structure With TOPCon Passivation Contacts

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Solution Overview

Problem

Existing high-efficiency solar cell technologies like HBC and TBC face challenges in process window narrowness, high process difficulty, and high production costs, limiting their industrial application and efficiency improvement.

Innovation Solution

The use of a tunnel oxide layer and doped crystalline silicon layer, combined with an isolating structure, replaces intrinsic a-Si:H+a-Si:H(N) and SiOx+p-poly-Si layers in conventional HBC and TBC structures, reducing laser-induced thermal damage and high-temperature process issues, and incorporating oxide and silicon nitride passivation layers to improve surface passivation and reduce parasitic absorption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If intrinsic a-Si:H+a-Si:H(N) and SiOx+p-poly-Si layers are used in conventional HBC and TBC structures, then passivation effect is improved, but process window becomes narrow and process difficulty increases

Engineering Contradiction:

Improvepassivation effectVSAvoidprocess window narrowness

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the material parameters from intrinsic a-Si:H to tunnel oxide layer with specific thickness (1-5 nm), and from p-poly-Si to doped crystalline silicon layer with controlled doping concentration (10^19-10^21 cm^-3). These parameter changes broaden the process window while maintaining passivation effect.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures: tunnel oxide layer combined with doped crystalline silicon layer, and oxide passivation layer combined with silicon nitride passivation layer. These composite structures achieve effective passivation while simplifying the manufacturing process.

Inventive Principle:

Principle #40Composite materials

2Power

If conventional HBC and TBC structures are used, then conversion efficiency is improved, but production cost increases

Engineering Contradiction:

Improveconversion efficiencyVSAvoidproduction cost

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

The patent replaces expensive intrinsic a-Si:H deposition processes with more economical tunnel oxide layer formation through thermal oxidation or PECVD, and uses standard doped crystalline silicon layers instead of complex p-poly-Si structures. This reduces production cost while maintaining the conversion efficiency at 24%-26%.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Loss of energy

If oxide passivation layer and silicon nitride passivation layer are incorporated, then parasitic absorption is reduced, but device complexity increases

Engineering Contradiction:

Improveparasitic absorptionVSAvoidstructure complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The oxide passivation layer serves multiple functions: it provides electrical passivation of the silicon surface and acts as a barrier to reduce parasitic absorption. The silicon nitride passivation layer simultaneously provides anti-reflection coating functionality and electrical passivation. This multi-functionality reduces energy loss without significantly increasing structural complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 approach broadens the process window, reduces production costs, and enhances the energy conversion efficiency, open-circuit voltage, and short-circuit current, achieving performance comparable to existing HBC structures while minimizing parasitic absorption and reflectivity.

Implementation Method 1

tunnel oxide passivated contact (TOPCON) solar cells

Methodology Applied

Scientific EffectPassivation:

Implementation Method 2

doped crystalline silicon layer, where the tunnel oxide layer is located in the first region, and the doped crystalline silicon layer is located on a surface of the tunnel oxide layer

Methodology Applied

Scientific EffectField effect: Electric Field

Implementation Method 3

an isolating structure, where the isolating structure includes an isolating layer and an isolating groove

Methodology Applied

Scientific EffectElectrical insulation:

Implementation Method 4

Back-contact solar cell and preparation method therefor

Methodology Applied

Scientific EffectPhotovoltaic effect: Photovoltaic Effect

Data Source

PatentUS12568711B2Back-contact solar cell and preparation method therefor

Publication Date: 2026.03.03 LONGI GREEN ENERGY TECH CO LTD

AI summary

The present application discloses a back-contact solar cell and a preparation method thereof. The back-contact solar cell includes: a semiconductor substrate; a tunnel oxide layer and a doped crystalline silicon layer, where the tunnel oxide layer is located in a first region, and the doped crystalline silicon layer is located on a surface of the tunnel oxide layer away from the semiconductor substrate; an intrinsic non-crystalline silicon layer and a doped non-crystalline silicon layer where the intrinsic non-crystalline silicon layer is located in a second region and extends on part of a surface of the doped crystalline silicon layer away from the tunnel oxide layer, and the doped non-crystalline silicon layer is located on a surface of the intrinsic non-crystalline silicon layer away from the semiconductor substrate; and an isolating structure including an isolating layer and an isolating groove.