Photo-Assisted Charging for Electrochromic Devices

Nanotechnologies : Physical Science Apps

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  • Delia Milliron, Ph.D. , Chemical Engineering
  • Yang Wang, Ph.D. , Chemical Engineering

Background/unmet need

Electrochromic films, materials capable of darkening upon exposure to electrochemical bias or tinting on demand, must be supplied with electrical power in order to operate. Early development efforts have focused on H2 gas reduction or electrochemical reduction of lithium metal to generate electrons that effectively power the system.

Invention Description

In working with WO3 electrochromic materials, researchers at The University of Texas at Austin have developed a film designed to power itself in the presence of sunlight. WO3 is known as a wide bandgap semiconductor, capable of absorbing solar energy and converting it to electrons. These electrons could be transferred and stored at a counter electrode such as CeO2, essentially creating a solar cell battery used to power a smart window.


  • Efficient use of abundant solar energy to power the system
  • Mitigation of degradation pathways associated with alternative charging strategies
  • More cost effective and scalable than H2 reduction or lithium metal reduction


  • Efficient use of sunlight as the power source
  • Cost-effective means of generating power

Market potential/applications

Smart windows are a growing element of green-building processes being expanded in response to global climate concerns and the need for energy-efficient structures. Although currently an emerging market, the demand will grow dramatically over the coming decade. 

Development Stage

Proof of concept

IP Status

  • 1 PCT patent application filed