Upconversion Phosphor Luminescent Paint for Sunlight-Driven UVC

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Solution Overview

Problem

Existing upconversion phosphors require high-power-intensity visible light sources to emit UVC radiation, making them impractical for outdoor applications due to the low intensity of natural sunlight and LED light sources, and current UVC sources like mercury lamps and AlGaN LEDs are inefficient and impractical for outdoor use.

Innovation Solution

Development of Praseodymium-doped upconversion phosphors with the formula Li—R—Si—O—F:xPr3+, where R is Y or Lu, capable of emitting UVC radiation when excited by low-power-intensity visible light, including sunlight and LED light, with a wavelength range of 250-350 nm.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If existing upconversion phosphors are used to convert visible light to UVC radiation, then UVC emission is achieved, but high-power-intensity visible light sources are required which are impractical for outdoor applications

Engineering Contradiction:

ImproveUVC emission intensityVSAvoidexcitation light power intensity

Core Design Contradiction:

Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The patent changes the compositional parameters of the phosphor material by doping with praseodymium ions at optimized concentrations (0.01-5 mol%) and adjusting the host matrix composition (LiY3(SiO4)3F2 and Li2SiO3 ratios) to enhance the upconversion efficiency and enable effective UVC emission under low-power visible light excitation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite phosphor materials combining multiple host matrices (LiY3(SiO4)3F2 and Li2SiO3) with praseodymium dopants to create a synergistic effect that improves overall upconversion performance and enables efficient UVC generation under solar illumination conditions

Inventive Principle:

Principle #40Composite materials

2Power

If mercury lamps or AlGaN LEDs are used as UVC radiation sources, then UVC radiation is produced, but they are inefficient and impractical for outdoor use due to thermal management issues and high power requirements

Engineering Contradiction:

ImproveUVC radiation outputVSAvoidthermal management efficiency

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent replaces conventional electrical UVC sources (mercury lamps and AlGaN LEDs) with a phosphor-based optical conversion system that transforms visible light energy into UVC radiation, eliminating the need for complex thermal management systems and high-power electrical infrastructure

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces upconversion phosphor materials as an intermediary substance that converts low-energy visible photons into high-energy UVC photons, enabling efficient energy transfer without the thermal losses associated with direct electrical-to-UVC conversion methods

Inventive Principle:

Principle #24Intermediary (Mediator)

3Illumination intensity

If blue lasers with high power-intensity (1-1000 W/cm2) are used to excite Pr3+-doped UC phosphors, then UVC luminescence is generated, but such high-power sources are not available in natural sunlight or LED light which have intensities lower than 100 mW/cm2

Engineering Contradiction:

ImproveUVC luminescence intensityVSAvoidexcitation light intensity

Core Design Contradiction:

Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The patent optimizes the phosphor composition parameters including Pr3+ doping concentration (0.01-5 mol%), host matrix ratios, and sintering conditions to maximize absorption cross-section and upconversion quantum efficiency, enabling effective UVC generation under low-intensity excitation sources

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent enhances the phosphor material properties in compositional and structural dimensions through controlled doping and host matrix selection, thereby improving the energy conversion efficiency across the optical spectrum to bridge the gap between available solar/LED intensity and required excitation intensity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 phosphors effectively convert low-energy visible light into UVC radiation, enabling practical outdoor applications such as disinfection and photocatalysis without the need for high-power light sources.

Implementation Method 1

Praseodymium (Pr3+) doped UC phosphors are used in developing sunlight to UVC or visible light to UVC because the energy level structure of Pr3+ allows emitting one UVC photon at around 265 nm to 275 nm after sequentially absorbing two lower-energy visible photons in a two-step UC process

Methodology Applied

Scientific EffectUpconversion: Photoluminescence

Data Source

PatentUS20250289999A1Luminescent paint containing upconversion phosphor

Publication Date: 2025.09.18 KING FAHD UNIVERSITY OF PETROLEUM AND MINERALS

AI summary

An upconversion phosphor having a formula of Li—R—Si—O—F:xPr3+, where R is yttrium (Y) or lutetium (Lu). The value of x is 0.001 to 5 and represents a mole percentage (%) based on the total number of moles of all elements in the upconversion phosphor. Following excitation with sunlight, the upconversion phosphor emits light with a wavelength in the range of 250 nanometers (nm) to 350 nm.