Photodetectors play a crucial role in the field of optoelectronic communications and other information-related domains. Si as one of the most important materials for visible light detection, has its performance constrained by factors such as its low absorption coefficient, which limits the further enhancement of commercial photodetector performance. In this work, by employing a SnO 2 heterojunction, we have fabricated a MSM structured photodetector with a vertical PN space charge region. The photoelectrons generated in the space charge region can be accelerated onto the SnO 2 surface and achieve sensitive spectral response. By varying the thickness of SnO 2 , the thickness of the space charge layer in the detector is gradiently modulated. Together with the photo-induced potential from KPFM characterization, the key role of the space charge layer thickness is fully confirmed in performance modulation of devices. The device achieves a maximum responsivity of 0.65 A/W and a quantum efficiency of 94.6 %. More notably, the transient response of the device is below 20 ns, demonstrating the application potential of this structure in photodetectors.
Perovskite quantum dots light-emitting diodes (PeLEDs) have been developed for next-generation high resolution display applications. However, the hindered charge injection and massive charge trapping due to the insulating and defective surface of quantum dots (QDs) usually lead to a slow rise in electroluminescence (EL) response, which makes it challenging to realize ultra-high refresh rate displays with nanosecond response. Herein, an ionic liquid 1-Butyl-3-methylimidazolium Trifluoromethanesulfonate ([BMIM]OTF) was used to enhance the crystallinity and reduce the surface area ratio of QDs, which effectively decreases defect state and injection barrier at the interface. Therefore, the rise time of EL response with steady-state is successfully reduced by over 75%. We further reduce the capacitance effect by decreasing the light-emitting unit area. Thus, ultra-high resolution (9072 pixel per inch) PeLEDs with light-emitting pixel size of 1.3 μm were realized, achieving a brightness exceeding 170,000 cd/m 2 and an external quantum efficiency up to 15.79%. Moreover, it achieves nanosecond ultrafast response time under steady-state, which is the fastest response time of PeLEDs reported so far. Our work represents the most advanced performance of ultra-high-resolution PeLEDs, and provides in-depth insights into the mechanism of improving their response speed, showing significant potential in high refresh rate active display application.
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