Feb 18th 2026|Phoenix, Arizona|3 min read
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The unusual electronic and optical properties of perovskites have long been touted as useful for improving solar cells and television screens, but these materials have never quite hit the big time. Existing approaches have hoovered up all the investment and attention, and perovskites remain confined to specialist applications.
A niche is now opening, however, in which there are no incumbents. For, as a session at this year’s annual meeting of the American Association for the Advancement of Science, in Phoenix, Arizona, heard, perovskites could be just the thing for making so-called neuromorphic computers, which would process information in a similar way to brains.
Conventional computers have separate memory and processor units, between which data have to shuttle in a time- and energy-consuming fashion. Neuromorphic computers would eliminate this by processing data and storing them in the same piece of hardware, as happens in a brain. In this organ neurons and the synaptic junctions between them contrive to do both jobs simultaneously.
Perovskites, named after a mineral discovered in the Urals in the 19th century, are compounds with the chemical formula ABX3, where A and B are positively charged metal ions and X is a negatively charged non-metallic ion. In a perovskite crystal lattice these ions are arranged into octahedra that have large spaces between them.
Depending on the identities of A, B and X—and particularly on whether X is a halide (a group that includes chloride, bromide and iodide)—this arrangement permits other atoms to enter the crystal structure and thereby change the perovskite’s properties. Including, as Wolfgang Tress, of Zurich University of Applied Sciences, explained to the meeting, its electrical ones. Choosing the right ions can allow a halide perovskite to have an electrical resistance that switches between high and low when a current is passed through it, making it what is known as a memristor. As memristors can stand in for both neurons and synapses, they could be used to build a neuromorphic computer.
Dr Tress works on the synapse side of things. Real synapses become more effective with use and dwindle with neglect. Dr Tress’s artificial ones mimic this by changing how readily they pass current. Using silver electrodes encourages silver atoms to leak into the perovskite. Here they form highly conductive but fragile filaments. As long as these filaments remain intact, the memristor has low resistance. When they break, its resistance rises. Applying a current to a memristor can either make or break the filaments, depending on its voltage. Crucially, once filaments are broken or repaired they stay that way until actively changed by the application of an appropriate voltage. These changes, by altering how current flows through a network of memristors, act both to store data and to permit its processing.
To replicate a neuron, as Bruno Ehrler, of AMOLF, a physics-research institute in Amsterdam, explained, you need to combine a memristor with a capacitor. Real neurons work by combining the signals they receive from other neurons and, if and when the result exceeds a particular threshold, generating an electrical spike of their own. Capacitors are temporary stores of electric charge, so can act as adding machines for incoming current. Once the amount of charge in such a capacitor exceeds a pre-ordained threshold, it discharges through the memristor, altering its resistance and permitting it to pass an electrical spike on to the wider network.
As with a conventional computer, which employs transistors and capacitors as its basic components, building a neuromorphic equivalent involves connecting memristors and capacitors. Dr Ehrler reckons a prototype network might be put together as soon as next year. Whether the neuromorphic upstarts will win their place in the spotlight remains to be seen. ■
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This article appeared in the Science & technology section of the print edition under the headline “Peerless perovskites”
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