Sensitive, High‐Speed, and Broadband Perovskite Photodetectors with Built‐In TiO₂ Metalenses

Abstract

Nowadays photodetectors primarily rely on inorganic semiconductors including silicon and III-V compounds. [6][7][8][9][10] But the fabrication of these devices requires costly, size-limited epitaxial growth methods that are not compatible with on-chip integration and mass production. [11,12] Therefore, increasing interests have been evoked recently to produce cost-effective photodetectors consisting of solution-processable materials. [1,[13][14][15] Metal-halide perovskites have emerged with considerable potential as the next-generation materials of photodetectors because of their ease of processing, tailorable optoelectronic properties, and compatibility with flexible substrates. [12,16] Following the development pathway of perovskite photovoltaics, material scientists have reported perovskite photodetectors with an n-i-p structure using mesoporous TiO 2 (meso-TiO 2 ) at the early stage. [14,17,18] Although being an excellent electron transporting layer (ETL) for photovoltaics, meso-TiO 2 has been found to show large capacitance leading to slow response to an Monolithic integration of nanostructured metalenses with broadband light transmission and good charge transport can simultaneously enhance the sensitivity, speed, and efficiency of photodetectors. The realization of built-in broadband metalenses in perovskite photodetectors, however, has been largely challenged by the limited choice of materials and the difficulty in nanofabrication. Here a new type of broadband-transmitting built-in TiO 2 metalens (meta-TiO 2 ) is devised, which is readily fabricated by one-step and lithographfree glancing angle deposition. The meta-TiO 2 , which comprises of sub-100 nm TiO 2 nanopillars randomly spaced with a wide range of sub-wavelength distances in 5-200 nm, shows high transmittance of light in the wavelength range of 400-800 nm. The meta-TiO 2 also serves as an efficient electron transporting layer to prevent the exciton recombination and facilitate the photoinduced electron extraction and transport. Replacing the conventional mesoporous TiO 2 with the meta-TiO 2 comprehensively leads to enhancing the detection speed by three orders of magnitude to a few hundred nanoseconds, improving the responsivity and detectivity by one order of magnitude to 0.5 A W −1 and 10 13 Jones, respectively, and extending the linear dynamic range by 50% to 120 dB.

Remarkable Enhancement of Detectivity and Stability in Flexible n–i–p-Type Perovskite Photodetectors by Concurrent Use of Various Two-Dimensional Materials: Doped Graphene, Graphene Quantum Dots, WS2, and h-BN

“…This D * value is larger than or comparable to those of previously reported self-powered n–i–p-type perovskite-based PDs (Table ). ,,,− …”

All‐Oxide Transparent Photodetector Array for Ultrafast Response through Self‐Powered Excitonic Photovoltage Operation

“…[ 1–4 ] UV‐reactive wide‐bandgap materials have strong UV absorption and are applied in transparent and fast‐responsive photodetectors. [ 5,6 ] Transparent optoelectronics are devices that enable the transmittance of visible‐light illumination and see‐through features. These emerging transparent optoelectronics complement Si‐based electronics.…”

“…[1][2][3][4] UV-reactive wide-bandgap materials have strong UV absorption and are applied in transparent and fast-responsive photodetectors. [5,6] Transparent Can photodetectors be transparent and operate in self-powered mode? Is it possible to achieve invisible electronics, independent of the external power supply system, for on-site applications?…”

Laser nanostructured gold biosensor for proto-oncogene detection

“…Super-Resolution variants of LDW (SR-LDW) have also been developed, and these have been successfully applied to the fabrication of nanoscale Micro-Electro-Mechanical Systems (MEMS) 18 . The emergence of LDW as a metalens fabrication technique would be unsurprising as similar, less flexible techniques like glancing angle deposition (GLAD) have already been demonstrated to be highly effective for metalens fabrication, allowing for their rapid and inexpensive production 19 .…”