FeS2 Photovoltaic Battery with Ionic Liquid Passivation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Iron pyrite (FeS2) based photovoltaic devices face efficiency limitations due to low conductivity, high surface trap states, and degradation issues, particularly in iodide/triiodide aqueous electrolytes, which hinder their application in energy harvesting and storage devices.
Innovation Solution
The development of FeS2-based photovoltaic battery (PVB) devices incorporating a transparent substrate, a porous film of FeS2 nanocrystals, and a halide ionic liquid, which absorbs photons to generate a current and voltage, enabling charge separation and storage, with the halide ionic liquid passivating the FeS2 nanocrystals to enhance electronic coupling and reduce degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If FeS2 nanocrystals are used in photovoltaic devices, then light harvesting capability is improved due to high photoabsorption coefficient and ideal bandgap, but charge transfer and transport are hindered due to low conductivity and high surface trap states
Solution Approach 1:
The patent introduces an ionic liquid as an intermediary substance that infiltrates the porous FeS2 nanocrystal film. This ionic liquid acts as a mediator to improve charge transfer and transport by reducing surface trap states and enhancing electronic coupling between FeS2 nanocrystals, thereby resolving the contradiction between light harvesting capability and charge transfer efficiency
Solution Approach 2:
The patent modifies the surface properties of FeS2 nanocrystals by treating them with ionic liquids, which changes the electrical and surface characteristics. This parameter change reduces surface trap states and improves conductivity, enabling better charge transfer while maintaining the inherent light harvesting properties of FeS2
2Quantity of substance
If FeS2 is used in photovoltaic devices, then theoretical capacity is improved with high value of 890 mAh/g, but stability deteriorates due to degradation in iodide/triiodide aqueous electrolyte
Solution Approach 1:
The ionic liquid serves as a protective intermediary between FeS2 and the aqueous electrolyte, preventing direct contact and degradation reactions. This intermediary layer maintains the stability of FeS2 composition while allowing the high theoretical capacity to be utilized in battery applications
Solution Approach 2:
The patent creates an inert environment by using ionic liquid as a protective medium that prevents FeS2 from degrading in the presence of iodide/triiodide aqueous electrolyte. This inert environment preserves the compositional stability of FeS2 while maintaining its high capacity characteristics
3Stability of the object's composition
If organic ligands are used to surround FeS2 nanocrystals, then nanocrystal stability is improved, but charge transfer and electronic coupling are reduced due to long chain length of one to several nanometers
Solution Approach 1:
The patent changes the parameter of ligand chain length from one to several nanometers to approximately 0.5 nm by using shorter molecules like ethanedithiol. This parameter change improves electronic coupling and charge transfer while maintaining adequate nanocrystal stability through the shortened ligand layer
Solution Approach 2:
The patent applies different ligand characteristics to different functional requirements: shorter ligands for electronic coupling and charge transfer, while the FeS2 nanocrystal core provides structural stability. This local quality differentiation resolves the contradiction between stability and electronic coupling
4Ease of manufacture
If FeS2 devices are developed independently for energy harvesting or energy storage, then device optimization is simplified, but overall system efficiency is reduced due to lack of integration
Solution Approach 1:
The patent merges photovoltaic and battery functions into a single integrated FeS2-based device. The same FeS2 nanocrystal active layer serves both as the photoactive material for energy harvesting and as the electrode material for energy storage, eliminating the need for separate device development while achieving high overall system efficiency through unified optimization
Solution Approach 2:
The patent creates a multi-functional device where FeS2 nanocrystals perform multiple functions: light absorption and charge generation for photovoltaics, and high-capacity lithium ion storage for batteries. This universality allows a single device structure to achieve both energy harvesting and storage with optimized performance
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 FeS2-based PVB devices achieve a power conversion efficiency of up to 4.07% and specific capacity of 57.8 mAhg−1, demonstrating improved charge transfer and stability, suitable for both energy harvesting and storage applications.
Implementation Method 1
photons incident on the active layer are absorbed by the FeS2 nanocrystals, generating a current and a voltage, whereby a separation of charge within the active layer is created
Data Source
AI summary
Provided are FeS2 based photovoltaic battery devices comprising a transparent substrate, an active layer disposed over the transparent substrate, the active layer comprising a porous film of FeS2 nanocrystals and a halide ionic liquid infiltrating the porous film, and an electrode disposed over the active layer. The device may be configured such that under exposure to light, photons incident on the active layer are absorbed by the FeS2 nanocrystals, generating a current and a voltage, whereby a separation of charge within the active layer is created, which is discharged in the absence of the light.