Photoluminescence Spectroscopy for OLED Metrology
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current metrology techniques for OLED devices are time-consuming and inadequate for real-time monitoring of layer uniformity and dopant concentration, leading to delayed detection of process excursions and increased yield loss.
Innovation Solution
An apparatus comprising a light source, optical assembly, and detector configured to perform in-situ, non-destructive monitoring of photoluminescent layers using static and nanosecond transient photoluminescence spectroscopy, enabling real-time determination of dopant concentration and film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional metrology techniques are used for OLED devices, then measurement accuracy is improved, but measurement time increases and real-time monitoring is not achieved
Solution Approach 1:
The patent replaces conventional mechanical/optical metrology systems with photoluminescence spectroscopy. The system uses a light source to excite the organic layer, which emits photoluminescence signal detected by a spectrometer. This optical substitution enables faster measurement (seconds vs. hours) while maintaining accuracy through spectral analysis of the emitted light, directly resolving the time-accuracy contradiction.
Solution Approach 2:
The patent changes the measurement parameter from conventional optical properties (absorbance, reflectance) to photoluminescence emission characteristics. By measuring the intensity, wavelength, and lifetime of photoluminescence signals, the system achieves both rapid measurement and high precision in determining organic layer properties such as thickness, dopant concentration, and molecular orientation.
2Reliability
If conventional metrology techniques are used, then comprehensive characterization is achieved, but detection speed decreases and process excursion detection is delayed
Solution Approach 1:
The patent implements continuous or near-continuous photoluminescence measurement during the organic layer deposition process. The measurement system remains active throughout deposition, providing continuous feedback on layer formation quality. This enables immediate detection of process excursions while maintaining comprehensive characterization through multi-parameter photoluminescence analysis.
Solution Approach 2:
The patent establishes a closed-loop feedback system where photoluminescence measurements are continuously taken during deposition, analyzed in real-time, and used to adjust deposition parameters. This feedback mechanism ensures high reliability in process monitoring by immediately detecting and correcting deviations, while the rapid nature of photoluminescence measurement maintains high detection speed.
3Manufacturing precision
If metrology is performed after all organic layers are deposited, then complete device structure is available for measurement, but yield loss increases due to delayed defect detection
Solution Approach 1:
The patent performs photoluminescence measurements during or immediately after each organic layer deposition step, rather than waiting for complete device assembly. This preliminary measurement approach detects defects early in the manufacturing process, allowing immediate corrective action before subsequent layers are deposited, thereby preventing yield loss while maintaining control over final layer uniformity.
Solution Approach 2:
The patent divides the measurement process into segmented steps corresponding to each organic layer deposition. Instead of a single end-point measurement, the system performs sequential photoluminescence measurements on individual layers (e.g., electron transport layer, emissive layer, hole transport layer) as they are formed. This segmentation enables early defect detection and maintains both manufacturing precision and productivity.
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
Enables fast and accurate monitoring of OLED layer characteristics, allowing for immediate detection of process issues and reducing production losses by providing reliable feedback during the deposition process.
Implementation Method 1
an optical assembly configured to direct the excitation light onto a photoluminescent (PL) layer formed on a substrate that is disposed in a system for depositing the PL layer; a detector that is configured to receive a PL emission generated by the PL layer in response to the excitation light interacting with the PL layer
Data Source
AI summary
An apparatus for determining a characteristic of a photoluminescent (PL) layer comprises: a light source that generates an excitation light that includes light from the visible or near-visible spectrum; an optical assembly configured to direct the excitation light onto a PL layer; a detector that is configured to receive a PL emission generated by the PL layer in response to the excitation light interacting with the PL layer and generate a signal based on the PL emission; and a computing device coupled to the detector and configured to receive the signal from the detector and determine a characteristic of the PL layer based on the signal.