Perovskite Solar Cell Capping Layer for Stable Charge Extraction

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Solution Overview

Problem

The long-term stability of organic-inorganic halide perovskite solar cells is hindered by decomposition at the interface between perovskites and charge transporting layers due to high defect density, interface charge accumulation, and ion migration, leading to non-radiative recombination losses and degradation.

Innovation Solution

A novel perovskite solar cell structure incorporating a capping layer composed of an organic-inorganic hybrid perovskite, specifically 2-(3′″,4′-dimethyl-[2,2′:5′,2″:5″,2′″-quaterthiophen]-5-yl)ethan-1-ammonium iodide (4Tm), which forms a densely packed layer on the perovskite surface, facilitating charge extraction, improving energy band alignment, reducing interface recombination, and stabilizing the lattice.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If interface modification is applied to passivate defects and stabilize the surface lattice, then stability is improved, but charge transfer is inhibited due to electrically insulating layers

Engineering Contradiction:

ImprovestabilityVSAvoidcharge transfer

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent changes the electrical parameter of the interface modification layer by using conductive polymers (PEDOT:PSS, PTAA, TAPC) instead of insulating materials. This parameter change allows the layer to simultaneously passivate defects and facilitate charge transfer, resolving the contradiction between stability improvement and charge transfer inhibition

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite interface modification layers combining organic-inorganic hybrid perovskites with conductive polymers. This composite structure provides both the defect-passivation capability of perovskites and the charge transport ability of conductive polymers, achieving both stability and efficient charge transfer

Inventive Principle:

Principle #40Composite materials

2Reliability

If conventional interface modification materials are used, then surface passivation is achieved, but non-radiative recombination losses increase

Engineering Contradiction:

Improvesurface passivationVSAvoidnon-radiative recombination losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent changes the electrical conductivity parameter of the interface modification layer by selecting conductive materials (PEDOT:PSS, PTAA, TAPC) with high hole mobility. This parameter change reduces charge accumulation and non-radiative recombination while maintaining surface passivation, thereby reducing energy losses

Inventive Principle:

Principle #35Parameter changes

3Productivity

If charge transporting layers are added for efficient charge extraction, then power conversion efficiency is improved, but decomposition at the interface increases due to high defect density and ion migration

Engineering Contradiction:

Improvepower conversion efficiencyVSAvoiddecomposition resistance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent introduces organic-inorganic hybrid perovskite layers (such as (PEA)2PbI4 and (BA)2PbI4) as intermediary buffer layers between the perovskite active layer and charge transporting layers. These intermediary layers passivate interface defects, reduce ion migration, and prevent direct contact between charge transporting layers and perovskite, thereby preventing decomposition while maintaining efficient charge extraction

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent uses composite interface modification structures combining organic-inorganic hybrid perovskites with conductive polymers (PEDOT:PSS, PTAA, TAPC). This composite structure provides both defect passivation from the perovskite component and charge transport capability from the polymer component, achieving both high efficiency and stability

Inventive Principle:

Principle #40Composite materials

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 4Tm capping layer enhances the power conversion efficiency to 22.06% with improved stability under illumination, suppressing phase segregation and ion migration, and maintaining a robust interface between perovskite and hole transporting layers.

Implementation Method 1

Organic-inorganic halide perovskite solar cells (PSCs) have seen a rapid increase in power conversion efficiency (PCE), reaching a certified value of over 25% for laboratory scale devices

Methodology Applied

Scientific EffectPhotovoltaic Effect: Photovoltaic Effect

Implementation Method 2

These issues not only leave the perovskite vulnerable to degradation, but also are sources of non-radiative recombination losses in the devices

Methodology Applied

Scientific EffectNon-radiative recombination:

Data Source

PatentUS12435100B2Perovskite solar cells

Publication Date: 2025.10.07 PURDUE RES FOUND

AI summary

The present disclosure relates to novel perovskite solar cells, and the method of making and using the novel perovskite solar cells. More specifically, a triple cation perovskite solar cell device containing a multifunctional capping layer (MCL) of R1NH3+ and/or a thin layer of two-dimensional (2D) material of (R1NH3+)2(A+)n−1(M2+)n(X−)3n+1 on top of the commonly used ABX3 perovskite, with enhanced power conversion efficiency of 22.06% (from 19.94%) with long-term stability over 1000 hours under continuous illumination has been developed.