Room-Temperature Titanium Oxide ETL via Sol-Gel
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Solution Overview
Problem
Organic solar cells require efficient electron transporting layers (ETLs) that do not need thermal annealing, as current methods are energy demanding and can damage the organic active layer.
Innovation Solution
A solution-based process for forming a titanium oxide ETL layer under inert atmosphere, mixing an acid, water, a water-miscible alcohol, a titanium oxide precursor, and a compound like ethanolamine, without heating, to create a clear solution that can be spin-coated without further treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal annealing is used to improve conductivity of ETL layer, then electron mobility increases, but energy consumption increases and organic active layer may be damaged
Solution Approach 1:
The patent changes the chemical composition parameters of the sol-gel solution by incorporating specific organic acids (acetic acid, formic acid, or propionic acid) and their salts, along with controlled water content and alcohol type. These compositional parameter changes enable the titanium oxide precursor to undergo hydrolysis and condensation at room temperature, forming a conductive ETL layer without thermal annealing, thus resolving the contradiction between achieving high conductivity and reducing energy consumption
Solution Approach 2:
The patent introduces organic acid intermediaries (acetic acid, formic acid, or propionic acid) and their salts as mediators in the sol-gel process. These intermediaries facilitate the hydrolysis and condensation of titanium oxide precursor at room temperature by providing a controlled chemical environment, enabling ETL formation without high-temperature treatment and preventing damage to the organic active layer
2Reliability
If thermal annealing in air is performed, then ETL conductivity improves, but organic active layer oxidizes and loses opto-electronic properties
Solution Approach 1:
The patent performs the entire sol-gel process, including mixing, hydrolysis, condensation, and ETL formation, under an inert atmosphere (nitrogen or argon). This inert environment prevents oxygen from reaching and oxidizing the organic active layer while still allowing the titanium oxide precursor to undergo chemical transformations through the controlled addition of water and organic acids, thus achieving high conductivity without oxidation damage
3Productivity
If heating of sol-gel solution is applied, then hydrolysis and condensation processes accelerate, but energy consumption increases and process complexity increases
Solution Approach 1:
The patent designs a self-service sol-gel system where the organic acid components (acetic acid, formic acid, or propionic acid) and their salts automatically catalyze the hydrolysis and condensation of titanium oxide precursor at room temperature. The system self-regulates the reaction rate through the inherent chemical properties of the organic acids, eliminating the need for external heating while maintaining high productivity in ETL formation
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
This method produces an efficient, energy-saving ETL layer with improved conductivity and adherence, enhancing the performance and stability of organic photovoltaic cells without the need for thermal annealing.
Implementation Method 1
processing in air (e.g. the TiO solution is taken out into air for hydrolysis and condensation processes)
Implementation Method 2
processing in air (e.g. the TiO solution is taken out into air for hydrolysis and condensation processes)
Implementation Method 3
The final step after cooling to room temperature is to add 10 ml of an alcohol selected from methanol, ethanol or isopropanol to the mixture. After a 200 fold dilution with methanol, the TiOx sol-gel of Heeger is spincasted in air on top of an active layer.
Data Source
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AI summary
The present invention relates to a method comprising the steps of: a) mixing an acid with water thereby obtaining a first mixture, b) mixing said first mixture with a water miscible alcohol, thereby obtaining a second mixture, c) mixing a compound of general formula N(R1)(R2)(R3) to said second mixture, thereby obtaining a third mixture, d) waiting enough time for said third mixture to reach room temperature, e.g. from 10 to 15 minutes, e) adding a titanium oxide precursor to said third mixture, thereby obtaining said solution,