Virus-based Fabrication of Electrochromic Materials with Enhanced Functionality

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Virus-based fabrication of electrochromic materials with enhanced functionality
Professor Angela Belcher
Department of Biological Engineering, MIT
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Dong Yun
Department of Biological Engineering, MIT
Managed By
Michelle Hunt
MIT Technology Licensing Officer
Patent Protection

Method for synthesizing metal oxide nanocyrstals

US Patent 8,535,506
Virus-templated iridium oxide-gold hybrid nanowires for electrochromic application
Nanoscale, (2012) 4(11), 3405-3409


Electrochromic materials reversibly change color in response to light, heat, or an electric charge. They are used in the construction of “smart glass,” which fluctuates between translucent and transparent in order to block light and heat from passing through. Windows made with smart glass are able to save costs on heating, air-conditioning, and lighting. Smart glass is also used in automotive windows to optimize visibility by reducing light and glare and in aircrafts to block UV radiation and prevent heat build-up inside the cabin. 

Problem Addressed

Electrochromic—or “smart”—windows improve energy efficiency, provide privacy, and optimize lighting conditions. Critical factors in the production of smart glass include material costs, installation costs, durability, and the optimization of function. This virus-based method for the production of electrochromic materials generates uniquely functional electrochromic nanowires. The nanowires feature enhanced charge extraction (i.e., better colorization efficiency), enhanced color retention (10 days versus 600 seconds with traditional TiO2 devices), and an exceptionally rapid response rate (1 millisecond). Additionally, the virus-based fabrication method is simple, inexpensive, rapid, and can be performed in solution under ambient conditions.


This technology is a method for synthesizing iridium oxide-gold hybrid nanowires used to generate electrochromic devices. The nanowires are assembled via bacteriophage scaffolding. First, a phage display library is used to select for phage with an affinity for iridium oxide. Gold nanoparticles are chemically linked to this selected virus, which binds iridium oxide. Applying a high-voltage pulse results in the formation of hybrid iridium oxide-gold nanowires. The nanowires exhibit both anodic and cathodic polarization and range in color from a bleached state to blue/black. The unique structure of the virus-based nanowires provides them with enhanced functionality that includes improved color retention and rapid charging and response times. Fabrication of the nanowires is performed rapidly in solution at room temperature and does not require further processing. 


  • Extremely rapid response rate
  • Improved charge extraction
  • Improved color retention
  • Decreased charging time
  • Low-cost production
  • Rapid production: nanowires form in under 1 minute without requiring further processing