Demonstration of thermal modulation using nanoscale and microscale structures for ultralarge pixel array photothermal transducers

Abstract

Large-pixel-array infrared emitters are attractive in the applications of infrared imaging and detection. However, the array scale has been restricted in traditional technologies. Here, we demonstrated a light-driven photothermal transduction approach for an ultralarge pixel array infrared emitter. A metal-black coating with nanoporous structures and a silicon (Si) layer with microgap structures were proposed to manage the thermal input and output issues. The effects of the nanoscale structures in the black coating and microscale structures in the Si layer were investigated. Remarkable thermal modulation could be obtained by adjusting the nanoscale and microscale structures. The measured stationary and transient results of the fabricated photothermal transducers agreed well with the simulated results. From the input view, due to its wide spectrum and high absorption, the black coating with nanoscale structures contributed to a 5.6-fold increase in the temperature difference compared to that without the black coating. From the output view, the microgap structures in the Si layer eliminated the in-plane thermal crosstalk. The temperature difference was increased by 340% by modulating the out-of-plane microstructures. The proposed photothermal transducer had a rising time of 0.95 ms and a falling time of 0.53 ms, ensuring a fast time response. This method is compatible with low-cost and mass manufacturing and has promising potential to achieve ultralarge-array pixels beyond ten million.

Ultralarge Pixel Array Photothermal Film based on 3D Self‐Suspended Microbridge Structure for Infrared Scene Projection

“…When the laser power density was 3.95 W cm −2 , the PCEs of Model A, B, and C photothermal films were 7.42%, 9.56%, and 12.47%, respectively. The PCEs of the microbridge array photothermal films were much higher than the reported PCE of 5.37% from a photothermal transducer, [18] and the highest PCE we proposed was more than twice the reported value. The results demonstrated that the photothermal films with 3D self-suspended microbridge arrays could improve the PCE effectively, which offered an important step forward in applications of thermal emitters and infrared scene generation.…”

“…Moreover, the temperature increasing slope was obtained by linear fitting. The temperature increasing slope of the three photothermal films were 52.55, 59.60, and 67.37 K W −1 cm −2 , respectively, which were much larger than 30.69 K W −1 cm −2 of the reported 3D photothermal transducer [ 18 ] and 44.20 K W −1 cm −2 of the reported 3D blackbody microcavity array. [ 27 ] Figure 6c compares the measured and simulated temperature increasing slope of the three photothermal films.…”

“…presented an improved photothermal transducer, they optimized the parameters of the film and obtained a frame rate of 200 Hz. [ 18 ] However, the highest temperature was 535.5 K under a laser power density of 7.9 W cm −2 . The reported temperature increasing slope with respect to input light intensity was 30.69 K per W cm −2 .…”