May 31, 2023
Perovskite devices power up
Nature Electronics volume 6, page 545 (2023)Cite this article 4204 Accesses 13 Altmetric Metrics details Metal halide perovskites are of increasing use in applications beyond conventional
Nature Electronics volume 6, page 545 (2023)Cite this article
Metal halide perovskites are of increasing use in applications beyond conventional photovoltaics, from flexible solar cells for wearable devices to field-effect transistors for unconventional computing.
Solar cell research has, in recent years, been dominated by work on perovskites. These perovskites are metal halide perovskites, such as methylammonium lead iodide (CH3NH3PbI3), which have the same crystal structure and general chemical formula as the mineral also known as perovskite, calcium titanate (CaTiO3). The work often focuses on creating large-scale photovoltaic technology that could outperform commercial approaches, which are led by crystalline silicon. But the features of these solution-processable materials — which include low-cost manufacturing and the ability to create flexible thin-film devices — mean they are also of potential value in more unconventional applications. To illustrate, in an Article in this issue of Nature Electronics, Martin Kaltenbrunner, Wei Gao and colleagues show that a perovskite solar cell can be used to power a wearable sweat sensor.
Wearable sensors typically rely on batteries for power. But these can be bulky and need to be recharged with an external source of electricity. Solar cells could provide a more lightweight and sustainable option. However, conventional silicon solar cells are rigid and fragile, and can struggle in low-light or indoor conditions. The researchers — who are based at the California Institute of Technology and Johannes Kepler University Linz — thus turned to perovskite solar cells, and a flexible quasi-two-dimensional perovskite solar cell module, in particular.
Their sweat sensor contains iontophoresis electrodes for sweat stimulation, microfluidics for sweat sampling, electrochemical sensors for sweat analysis, and an impedimetric sensor for sweat rate monitoring, as well as a Bluetooth-based system for wireless data transmission. Despite this long list of functionalities, with the perovskite solar cell module (which has a power conversion efficiency of more than 31% under indoor light illumination), the device can operate in a range of lighting conditions. The team show that the wearable sensor can continuously monitor a person’s physicochemical information — glucose, pH and sodium ion levels, as well as sweat rate and skin temperature — for more than 12 hours and during various indoor and outdoor physical activities. (See also accompanying News & Views article on the work from Jussi Hiltunen of the VTT Technical Research Centre of Finland.)
The attractive properties of metal halide perovskites include high carrier mobilities, long diffusion lengths and tunable bandgaps. And the materials have been extensively explored in other optoelectronic devices, including light-emitting diodes (LEDs)1, where progress has — like that of perovskite solar cells — been rapid. In applications beyond optoelectronic devices, developments have been slower. In particular, although work on perovskite field-effect transistors can be traced back to 1999 — where devices based on two-dimensional layered phenylethylammonium tin iodide ((C6H5C2H4NH3)2SnI4) were tested2 — the potential of such transistors has been uncertain. But recent results have provided encouragement.
In a Perspective article elsewhere in this issue, Huihui Zhu, Yong-Young Noh and colleagues consider the development of metal halide perovskite transistors. The researchers — who are based at institutes in South Korea, China, Italy and the United States — discuss the relevant electronic and structural properties of halide perovskite semiconductors, and examine the limitations of lead-based perovskite systems and the potential of tin-based perovskite systems to deliver high-performance devices. They also explore the potential applications of these perovskite field-effect transistors — from monolithic three-dimensional integrated circuits to neuromorphic optoelectronics — and highlight some of the challenges that need to be addressed to create practical devices and circuits.
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Perovskite devices power up. Nat Electron 6, 545 (2023). https://doi.org/10.1038/s41928-023-01028-5
Published: 24 August 2023
Issue Date: August 2023
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