Infrared-to-visible upconverters have widespread application prospects, including bioimaging, night vision, and defense security. A typical upconverter is generally constructed by integrating an infrared photodetector (PD) detecting low-energy infrared with a visible light-emitting diode (LED) emitting high-energy visible light. However, when photocarriers transport through the interface between PD and LED, lateral current spreading inevitably presents, which leads to optical cross-talking and hinders the realization of high-resolution and large-area infrared imaging. Here, near-infrared (NIR) upconverters are fabricated via the integration of silicon (Si) NIR detectors with organic LED (OLED) by complementary-metal-oxide-semiconductor compatible manufacturing processes. The pixelated indium tin oxide (ITO) electrodes introduced as the interfacial carrier transfer channel effectively suppress lateral current spreading and ensure that the photogenerated carrier of PD could transport into the OLED with well-defined spatial resolution. The Si-OLED upconverters possess wafer-level luminous area and large-scale fabrication capacity and realize high-resolution infrared imaging with a resolution as high as 3629 dpi. By changing the organic luminescent layer of OLED, the Si-OLED upconverters could emit red/ green/ blue visible light under NIR illumination with a low turn-on voltage of 3 V and excellent upconversion efficiency of 9.2%. Furthermore, the large-area Si-OLED upconverters exhibit flexibility with an infrared upconversion ability even under bending.
The solution‐processed organic optical sensors based on a‐Si TFT backplane have been realized, which indicate the comparable performance compared to a‐Si photodiode optical sensors. Furthermore, the organic sensors demonstrate an extremely low absolute sensitivity threshold (also known as Noise Equivalent Power, NEP), which is down to 2.1 nW/cm2 at 530nm.
We report a new type of capacitive active pixel sensor based on LTPS TFT backplane technology. It is a pixel design method for image sensors, which combines amplifiers and capacitors to form a pixel unit. Each pixel contains three transistors. This structure includes a capacitor as a sensing element, a reset transistor RST (T3), a row selector RS (T1), and a signal amplifier SF (T2). The advantage is to amplify the signal before reading, which is effective reduce the influence of noise and interference sources, so as to achieve high image quality. Based on the new capacitive active pixel sensor, a capacitive fingerprint sensor array was realized and the fingerprint image was successfully captured.
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