Copper Iodide Hole-Selective Contact for Low-Cost Silicon Solar Cells

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Solution Overview

Problem

Existing silicon solar cells face challenges in improving photoelectric conversion efficiency due to high process costs associated with boron doping and poor surface passivation properties of transition metal oxide layers, particularly in MoOx/Si cells.

Innovation Solution

A carrier-selective contact junction silicon solar cell is developed using a copper iodide thin film formed through a low-temperature annealing process, with a sandwich-structured multilayer film of copper iodide and iodine thin films to maintain excellent p-type semiconductor properties and adjust the composition ratio of the iodine source.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If boron doping is used to form a p-type semiconductor layer, then p-type semiconductor properties are achieved, but process cost increases

Engineering Contradiction:

Improvep-type semiconductor propertiesVSAvoidprocess cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive boron doping with a low-cost copper iodide thin film that can be deposited using simple evaporation or sputtering techniques. The copper iodide layer serves as a hole-selective contact without requiring costly doping processes, thereby reducing manufacturing cost while maintaining p-type semiconductor functionality

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the material parameter from boron-doped silicon to copper iodide thin film. This material substitution allows achieving p-type semiconductor properties through a different physical mechanism (intrinsic p-type character of copper iodide) rather than through doping, thus avoiding the high process costs associated with boron doping

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If transition metal oxide (MoOx) is used as a hole-selective contact layer, then manufacturing process is simplified, but surface passivation properties deteriorate

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidsurface passivation properties

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent creates a composite structure by depositing an aluminum oxide thin film on top of the copper iodide thin film. This composite structure combines the advantages of both materials: copper iodide provides excellent hole selectivity and p-type properties, while aluminum oxide provides superior surface passivation. The combination resolves the contradiction between manufacturing simplicity and passivation quality

Inventive Principle:

Principle #40Composite materials

3Reliability

If high-temperature processing is used to form semiconductor layers, then material properties are improved, but manufacturing complexity and cost increase

Engineering Contradiction:

Improvematerial propertiesVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the processing temperature parameter from high-temperature to low-temperature regime. Copper iodide can be deposited and annealed at relatively low temperatures (below 450°C) while maintaining excellent p-type semiconductor properties and hole-selective contact functionality. This reduces manufacturing complexity and cost without sacrificing material quality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a simple evaporation or sputtering process to deposit the copper iodide thin film, replacing complex high-temperature semiconductor fabrication processes. The low-temperature deposition technique simplifies the manufacturing process while producing functional hole-selective contact layers with good material properties

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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

The use of a copper iodide thin film enhances p-type semiconductor properties, simplifies the manufacturing process, and improves photoelectric conversion efficiency by reducing iodine vacancy and enabling easy adjustment of the iodine source composition.

Implementation Method 1

a single-film copper iodide thin film formed by low-temperature annealing a sandwich-structured multilayer film having copper iodide thin films layered on top and bottom surfaces of an iodine thin film

Methodology Applied

Scientific EffectAnnealing: Annealing

Data Source

PatentUS12557427B2Carrier-selective contact junction silicon solar cell and manufacturing method therefor

Publication Date: 2026.02.17 KOREA INSTITUTE OF INDUSTRIAL TECHNOLOGY

AI summary

A method of manufacturing a carrier-selective contact junction silicon solar cell includes: preparing a conductive silicon substrate; forming a first passivation layer and a second passivation layer on and under the conductive silicon substrate, respectively; forming an electron-selective contact layer under the second passivation layer; forming a hole-selective contact layer on the first passivation layer; forming an upper transparent electrode on the hole-selective contact layer; forming an upper metal electrode on the upper transparent electrode; and forming a lower metal electrode under the electron-selective contact layer. In forming the hole-selective contact layer, a sandwich-structured multilayer film is formed by depositing a copper iodide thin film on a top surface and a bottom surface of an iodine thin film, and a single-film copper iodide thin film is formed by low-temperature annealing the sandwich-structured multilayer film.