Electro-optical Device Nanocrystal Conductivity via Intermediary Layers
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Solution Overview
Problem
Previous electro-optical devices using nanocrystal films face conductivity issues due to poor exciton separation, limiting photocurrent generation, and gold electrodes form blocking contacts, hindering the study of intrinsic transport properties.
Innovation Solution
An electro-optical device structure with a substrate, a hole transporting material layer, a layer of semiconductor nanocrystals, and a second electrode, where the second electrode can be made of indium tin oxide, and the nanocrystal layer is thin and incomplete, allowing direct contact and enhanced conductivity through microcontact printing and post-deposition chemical treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If nanocrystal films are used in electro-optical devices, then optical properties can be tuned, but conductivity is poor due to poor exciton separation
Solution Approach 1:
The patent introduces organic charge transport layers as intermediary materials between the nanocrystal films and electrodes. These layers mediate charge extraction by providing pathways for hole and electron transport, resolving the conductivity issue without altering the nanocrystal optical properties. The charge transport layers act as bridges that facilitate exciton separation and charge carrier extraction.
Solution Approach 2:
The device structure combines nanocrystal materials with organic charge transport materials to create a composite system. This composite approach allows the nanocrystals to maintain their tunable optical properties while the organic layers provide the necessary charge transport pathways, achieving both optical functionality and electrical conductivity.
2Reliability
If gold electrodes are used, then good electrical contact is achieved, but blocking contacts are formed that hinder study of intrinsic transport properties
Solution Approach 1:
The patent removes gold electrodes from the device structure and replaces them with alternative electrode materials that do not form blocking contacts. This extraction of the problematic gold electrode component allows for the study of intrinsic nanocrystal transport properties without the confounding effect of gold-induced blocking behavior.
3Stability of the object's composition
If complete nanocrystal layers are deposited, then film continuity is achieved, but conductivity remains poor
Solution Approach 1:
The organic charge transport layers serve as mediators that enable conductivity in nanocrystal films regardless of their continuity. These layers provide alternative pathways for charge transport through the film, allowing conductivity to be achieved even when the nanocrystal layer itself is discontinuous or has poor intrinsic conductivity.
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 configuration enhances photocurrent generation by increasing conductivity and allowing charge carrier extraction, overcoming the limitations of previous devices and enabling the study of intrinsic transport properties.
Implementation Method 1
exposing a device to an excitation wavelength of light
Implementation Method 2
poor exciton separation, limiting photocurrent generation
Implementation Method 3
a layer including a hole transporting material arranged on the first electrode
Implementation Method 4
applying a voltage across the first electrode and the second electrode
Data Source
AI summary
An electro-optical device can include a plurality of semiconductor nanocrystals. In some circumstances, the device can omit an electron transporting layer.