High‐Resolution, Flexible, and Full‐Color Perovskite Image Photodetector via Electrohydrodynamic Printing of Ionic‐Liquid‐Based Ink

Abstract

Direct full‐color image photodetectors without dichroic prisms or sophisticated color filters have considerable advantages in target recognition and information acquisition for electronic eyes and wearable sensors. However, the ability to combine various multispectral semiconductors in a high‐resolution and cost‐effective manner is still challenging. Here, high‐resolution electrohydrodynamic (EHD) printing, together with ionic liquid methylammonium acetate (MAAc) as the solvent, is first introduced to directly integrate various spectral‐response perovskite films into a pixelized full‐color photodetector. EHD printing enables micro/nanopatterning by using high electrical force to induce jetting, and MAAc improves film quality with scant pinholes and large‐size grains by decreasing the perovskite growth rate. By optimizing the printing process and crystallization condition, 1 µm perovskite dot arrays are EHD printed; this is, to the best of knowledge, the smallest printed feature size of perovskite application. And the photodetector still achieves high R and D* values of 14.97 A W‐1 and 1.41 × 1012 Jones, respectively. Finally, an integrated flexible full‐color image photodetector is constructed, which successfully realizes light signal detection and color recognition, paving a versatile and competitive approach for future full‐color image sensors and artificial vision systems.

Hierarchical Artificial Compound Eyes with Wide Field-of-View and Antireflection Properties Prepared by Nanotip-Focused Electrohydrodynamic Jet Printing

“…As demonstrated in Figure a, the printed droplet diameter increased from 17.6 ± 0.6 μm to 32.4 ± 1 μm when the applied voltage increased from 1250 to 1500 V. It was found that the average diameter of the droplet increased with the enhancement of the pulse amplitude. Because a higher voltage induces a greater charge accumulation near the surface at the nanotip, more ink at the apex of the Taylor cone is emitted to the receiving substrate with larger droplet diameter …”

“…Because a higher voltage induces a greater charge accumulation near the surface at the nanotip, more ink at the apex of the Taylor cone is emitted to the receiving substrate with larger droplet diameter. 45 The pulse frequency determines the printing speed, and it also affects the diameter of the droplet. The photographs of printed dots with different pulse frequencies from 1 to 25 Hz are shown in Figure S5.…”

Advances in Photoelectric Detection Units for Imaging Based on Perovskite Materials

“…[70] Wang et al obtained the pixelated distribution of full-color perovskite PDUs for the first time by using ionic liquid methylammonium acetate (MAAc) as solvent and high-resolution EHD printing method. [53] Figure 2i is the schematic diagram of EHD printing process. On the one hand, the perovskite precursor solution was sprayed under the action of [51] Copyright 2017, American Chemical Society.…”

Ionic Liquid for Perovskite Solar Cells: An Emerging Solvent Engineering Technology

“…ILs as a precursor solvent are a breakthrough in PSCs, which allows the preparation of PSCs with excellent performance and long-term stability in ambient air by a simple spin coating method without auxiliary solvents. In addition, ILs as a solvent, e.g., MAAc, also show great advantages in other perovskite optoelectronic devices, including light-emitting diodes, memories, fluorescent materials, lasers, photodetectors, etc. Exploring related mechanisms is one of the ways to further improve the performance of optoelectronic devices and expand the application of ILs.…”