Multiferroic Buffer Layer Solar Cell Heterostructure
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Solution Overview
Problem
Current solar cells face limitations in power conversion efficiency due to factors like limited charge transport, energy barriers, and increased interfacial recombination at semiconductor-ferroelectric material interfaces, which hinder the development of high-efficiency solar cells with simplified structures and processing steps.
Innovation Solution
A heterostructure comprising a semiconductor solar cell with a buffer layer and at least one layer of multiferroic or ferroelectric material, where the multiferroic or ferroelectric material has a larger band gap than the semiconductor, enhancing carrier transport and absorption properties, and providing a self-polarized layer for improved photovoltaic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ferroelectric layers are formed on the front and rear surfaces of the semiconductor solar cell to increase open-circuit voltage and efficiency, then the photovoltaic efficiency is improved, but interfacial recombination loss increases due to heterojunction formation
Solution Approach 1:
A buffer layer is introduced as an intermediary between the semiconductor solar cell and the ferroelectric material layer. This buffer layer has a band gap larger than the semiconductor but smaller than the ferroelectric material, serving as a transition that reduces interfacial recombination while maintaining the beneficial effects of the ferroelectric layer on photovoltaic efficiency.
Solution Approach 2:
The solar cell structure is designed as a composite system comprising the semiconductor solar cell, the buffer layer with intermediate band gap, and the ferroelectric material layer. This composite structure combines the advantages of each material while mitigating their individual disadvantages, particularly the interfacial recombination issue.
2Stress or pressure
If ferroelectric materials with large band gap are used to increase open-circuit voltage, then the voltage is enhanced, but electron mobility is limited due to insulating effect
Solution Approach 1:
The buffer layer acts as a mediator that facilitates electron transport between the semiconductor and the ferroelectric material. With its intermediate band gap properties, it allows electrons to move more easily than through the large band gap ferroelectric material directly, thus improving electron mobility while still allowing the ferroelectric layer to provide high open-circuit voltage.
3Productivity
If conventional semiconductor solar cell structures are used with p-n junctions, then charge carriers are generated and separated, but power conversion efficiency is limited by energy barriers at interfaces and limited charge transport
Solution Approach 1:
The invention creates a composite structure combining semiconductor, buffer layer, and ferroelectric material with carefully selected band gap values. This composite approach improves power conversion efficiency by optimizing charge transport and reducing energy barriers, while the systematic layering actually simplifies the overall interface structure compared to conventional multi-layer approaches.
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 proposed structure significantly increases the photovoltaic efficiency of solar cells by improving carrier separation and absorption, reducing thermal losses, and simplifying processing steps, achieving up to 8% external power conversion efficiency with a fill factor of 0.68, while eliminating the need for additional processing steps like anti-reflection layers.
Implementation Method 1
when photons more energetic than the bandgap of the light absorbing semiconductor are absorbed by a junction, charge carriers, i.e. electrons and holes, are generated
Implementation Method 2
the photo-generated charge carriers of both polarities are driven by the polarization-induced internal electric field in opposite directions towards the cathode and the anode, respectively
Data Source
AI summary
A solar cell comprising a semiconductor solar cell of a first band gap; a buffer layer formed on a surface of the semiconductor solar cell; and at least one layer of a multiferroic or a ferroelectric material formed on the buffer layer; wherein the at least one layer of a multiferroic or a ferroelectric material has a second bang gap, the first band gap being smaller than the second band gap.