A semiconducting material that switches between glass and crystalline states at lower temperatures than conventional inorganic semiconductors

Unmet Need

In recent times, different forms of inorganic glasses have emerged that are distinct from what human civilization has been using for more than 5,000 years. Due to the advent of such glasses, a variety of applications have been made possible, ranging from their use in lenses, displays, circuit packaging, dielectrics, catalysts, solid state battery electrolytes, non-linear optics, optical communications and phase change memories. Phase change materials (PCM) have now been used in the development of optical data storage discs (CD/DVD), random access memory (RAM), and solid-state drives (SSD) in computing devices. Such devices are typically based on the switching characteristics of chalcogenide glasses, whereby the crystalline and amorphous states can be reversibly switched by exposure to different temperature cycles. One pertinent problem in such systems is the large power requirement in changing the state of the system, due to the relatively high melting point (>600 °C) of the most commonly used Germanium-Antimony-Telluride (GST)-based PCM. The quest to develop new high-quality semiconducting materials with lower melting points has thus far led to materials with limited semiconducting properties and potential applications.


Duke inventors have developed a material that switches between glass and crystalline states with distinct optoelectronic character and also melts at exceptionally low temperatures. This is intended for opening up new opportunities in applications such as nonvolatile memory, optical communication, and neuromorphic computing. Specifically, a 2D metal halide perovskite (MHP) was structurally tailored using bulky chiral organic cations to exhibit an unusual confluence of 175 °C melting point and inhibited crystallization. The chiral MHP can thus be meltquenched into a stable glassy state, otherwise inhibited in the analogous racemic MHP. Facile and reversible switching between glassy and crystalline states is demonstrated for the chiral MHP, each with distinct optoelectronic character.


  • A low-cost, low-power switchable glass compared to chalcogenide-based PCMs
  • Can be optimized for different applications by varying organic or metal cations or halogen anions used
Optical microscopy image of S‐NPB glassy film on the left and its eventual crystallization at 140 °C on the right. Scale bar is 250 µm. Images provided by Dr. David Mitzi.

Duke File (IDF) Number



  • Mitzi, David
  • Jana, Manoj
  • Singh, Akash

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Pratt School of Engineering