TOPCon Solar Cell Local Boron Doping to Reduce Lattice Loss

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Solution Overview

Problem

Conventional TOPCon solar cells experience lattice loss on the front surface due to full-surface boron diffusion, leading to a decrease in open-circuit voltage and photoelectric conversion efficiency.

Innovation Solution

A method for preparing a solar cell that involves forming a protective material layer on the first surface, removing part of it to create a local first doped region, and performing a first doping process to minimize lattice loss and enhance ohmic contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If full-surface boron diffusion is performed on the front side of the substrate, then a PN junction is formed on the front side of the cell, but lattice loss on the front surface is unavoidable, resulting in loss of open-circuit voltage and decrease in photoelectric conversion efficiency

Engineering Contradiction:

Improveopen-circuit voltageVSAvoidlattice loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies local quality by performing boron diffusion only in specific regions (first doped region and second doped region) rather than across the entire front surface. The first doped region is formed by removing protective material layer at preset positions and conducting localized doping, while the second doped region is formed similarly on the rear surface. This localized doping approach maintains the necessary PN junction formation while avoiding lattice loss in undoped areas, thereby preserving open-circuit voltage and improving photoelectric conversion efficiency.

Inventive Principle:

Principle #3Local quality

2Reliability

If full-surface boron diffusion is performed on the front side of the substrate, then a PN junction is formed on the front side of the cell, but a large number of composite centers are formed, resulting in loss of open-circuit voltage and decrease in photoelectric conversion efficiency

Engineering Contradiction:

Improvephotoelectric conversion efficiencyVSAvoidcomposite centers

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent implements local quality by restricting boron diffusion to specific first doped regions and second doped regions rather than applying it across the entire surface. The protective material layer is removed only at preset positions to define these doped regions, ensuring that doping occurs locally where needed for PN junction formation while avoiding the creation of harmful composite centers in other areas. This localized approach reduces the total number of composite centers and maintains higher photoelectric conversion efficiency.

Inventive Principle:

Principle #3Local quality

3Power

If full-surface boron diffusion is performed on the front side of the substrate, then splitting of exciton to electron and electron hole is achieved, but lattice distortion occurs leading to performance degradation

Engineering Contradiction:

Improvepower generationVSAvoidlattice structure

Core Design Contradiction:

PowerVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by conducting boron diffusion only in the first doped region and second doped region rather than across the entire substrate surface. The protective material layer is selectively removed at preset positions to define these localized doped regions. This approach maintains the necessary lattice structure stability in undoped areas while enabling exciton splitting and power generation in the doped regions where PN junctions are formed, thereby avoiding performance degradation from widespread lattice distortion.

Inventive Principle:

Principle #3Local quality

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 reduces lattice distortion on the front surface, thereby improving the open-circuit voltage and photoelectric conversion efficiency of the solar cell while maintaining short current and fill factor.

Implementation Method 1

removing a part of the protective material layer on a preset first doped region to prepare a protective layer

Methodology Applied

Scientific EffectChemical etching:

Implementation Method 2

performing a first doping process in the preset first doped region on the substrate

Methodology Applied

Scientific EffectThermal diffusion: Diffusion

Implementation Method 3

TOPCon cells have become relatively mature, taking into account both cost and efficiency

Methodology Applied

Scientific EffectPhotovoltaic effect: Photovoltaic Effect

Data Source

PatentUS20250107272A1Solar cell, method for preparing same and electrical device

Publication Date: 2025.03.27 HENGDIAN GRP DMEGC MAGNETICS CO LTD

AI summary

A solar cell, a method for preparing the same and an electrical device are provided. The method for preparing the solar cell includes following steps: providing a substrate, which includes a first surface and a second surface opposite to the first surface; forming a protective material layer on the first surface, and removing part of the protective material layer on a preset first doped region to prepare a protective layer; performing a first doping process in the preset first doped region on the substrate to prepare a substrate including a first doped region. A width of the first doped region is in a range of 10 μm to 35 μm.