Halide perovskite light-emitting electrochemical cells are a novel type of perovskite optoelectronic device that differs from the perovskite light-emitting diodes by a simple monolayered architecture.
The reported in the paper perovskite light-emitting electrochemical cell consists of a silicon substrate, multifunctional single composite perovskite layer (a mixture of halide perovskite microcrystals, polymer support matrix, and added mobile ions), and transparent single-walled carbon nanotube film top contact.
Due to silicon's good thermal conductivity, the device endures 40% lower thermal heating during operation compared to conventional ITO/glass substrate. Moreover, when a positive bias is applied to the device it yields a luminance of more than 7000 cd/m2 at 523 nm (green color).
When a negative bias is applied to the device it operates as a photodetector with a sensitivity up to 0.75 A/W (for wavelength in blue or UV regions), specific detectivity of 8.56-1011 Jones, and linear dynamic range of 48 dB. The technological potential of such a device is proven by the demonstration of a 24-pixel indicator display as well as successful device miniaturization by the creation of electroluminescent images with the smallest features less than 50 um.
The perovskite light-emitting electrochemical cells are a viable alternative to the conventional perovskite material devise research light-emitting diodes. Not only do perovskite light-emitting electrochemical cells imply having a much simpler architecture and design with one single functional layer replacing multiple active, charge-separation and transport layers of perovskite light-emitting diodes, but also perovskite light-emitting electrochemical cells can possess all extraordinary properties of LEDs, such as high efficiency, high color purity, and broad color gamut.
The reason why perovskite light-emitting electrochemical cells are capable of doing that - is completely different from the LEDs operation principle: when electrical bias is applied to the device, mobile positive and negative ions inside of the perovskite layer migrate towards corresponding electrodes dynamically forming a p-i-n structure inside of the perovskite layer, which allows effective electron-hole recombination with photon emission! Comprehensive research on various back-ups to conventional LED technology is a valuable source of diversifying the pool of industrial opportunities.
The reported device demonstrates exceptional light-emitting and light-detecting ("dual-functionality") characteristics alongside an enhanced in-operation heating durability. This is possible due to the utilization of silicon substrate in the perovskite light-emitting electrochemical cells design.
Silicon material is one of the stepping stones of the CMOS technology - complementary metal-oxide-semiconductor technology - technology used in manufacturing of all semiconductor chips, displays, etc. Integration of such an emerging material like perovskite material with silicon brings the R and D community one step closer to obtaining an industrial perovskite light-emitting electrochemical cell.
Last but not least, the broader context benefit of the reported device design - is its ITO-free transparent electrode based on single-walled carbon nanotubes. ITO - Indium-Tin Oxide- is a transparent conductive material widely used in perovskite photovoltaics and optoelectronics. Indium is a depleting element and, thus, the replacement of ITO by other materials based on earth-abundant elements would aid to prevail the indium deficiency in the industry.
Research Report:ITO-free silicon-integrated perovskite electrochemical cell for light-emission and light-detection
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St. Petersburg Academic University
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