Bilayer Hole Transport Layers for Stable Perovskite Solar Cells

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Solution Overview

Problem

Existing hole transport materials for perovskite solar cells do not simultaneously achieve high hole mobility, good energy alignment, formation of a good interface with perovskite absorbers, and robust chemical and thermal stability, limiting device performance and scalability.

Innovation Solution

A bilayer hole transport layer structure combining an inorganic and a thinner organic material is used, which improves device performance by reducing structural defects and interface recombination, enhancing layer morphology and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single hole transport material is used, then the device structure is simple, but it cannot simultaneously achieve high hole mobility, good energy alignment, good interface formation, and robust chemical and thermal stability

Engineering Contradiction:
Improvedevice performanceVSAvoidhole transport layer structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs a bilayer hole transport structure combining an inorganic layer (NiOx, CuOx, or CuSCN) with an organic layer (PTAA, P3HT, P3HT-COOH, or poly-TPD). This composite structure integrates the high hole mobility and thermal stability of inorganic materials with the good energy alignment and interface formation capabilities of organic materials, thereby achieving multiple performance requirements simultaneously that cannot be met by a single material.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The hole transport function is divided into two separate layers, each optimized for specific functions: the inorganic layer primarily provides hole mobility and thermal stability, while the organic layer primarily provides energy alignment and interface quality. This segmentation allows each layer to specialize in particular performance aspects without compromising the other functions.

Inventive Principle:
Principle #1Segmentation

2Reliability

If inorganic hole transporting materials are used, then high hole mobility and thermal stability are achieved, but poor interface formation with perovskite and low glass transition temperature occur

Engineering Contradiction:
Improvehole mobility and thermal stabilityVSAvoidinterface quality with perovskite
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The organic layer serves as an intermediary between the inorganic hole transport layer and the perovskite absorber layer. It mediates the interface formation, providing good energy alignment and interface quality while allowing the inorganic layer to maintain its high hole mobility and thermal stability. The organic material acts as a buffer that facilitates optimal interfacial contact without compromising the underlying inorganic layer's properties.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If organic hole transporting materials are used, then good energy alignment and interface formation are achieved, but low hole mobility and poor thermal stability occur

Engineering Contradiction:
Improveenergy alignment and interface qualityVSAvoidhole mobility and thermal stability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The hole transport functionality is segmented between two layers: the organic layer handles energy alignment and interface formation, while the inorganic layer handles hole mobility and thermal stability. This functional segmentation allows each material to excel at its specialized task without being constrained by the weaknesses of the other material type.

Inventive Principle:
Principle #1Segmentation

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 bilayer structure results in improved efficiency and stability of perovskite solar cells, with reduced surface recombination and resistance to halide-metal reactions, suitable for both N-I-P and P-I-N devices.

Implementation Method 1

improves device performance by reducing structural defects and interface recombination

Methodology Applied
Scientific EffectInterface recombination reduction:

Implementation Method 2

combining an inorganic and a thinner organic material is used, which improves device performance by reducing structural defects and interface recombination

Methodology Applied
Scientific EffectHole transport:

Implementation Method 3

resistance to halide-metal reactions

Methodology Applied
Scientific EffectChemical stability:

Data Source

PatentEP4292144B1Materials and methods for hole transport layers in perovskite photovoltaic devices
Publication Date: 2026.01.21 FIRST SOLAR INC
  • EP4292144B1 patent drawingFigure 1
  • EP4292144B1 patent drawingFigure 2
  • EP4292144B1 patent drawingFigure 3

AI summary

Methods and compositions for forming perovskite hole transport layers for use in manufacturing photovoltaic devices are described. Embodiments include using a plurality of hole transport materials to produce high-performance HTL contacts to improve performance and stability.