Thermal and optical properties of high-density GaN micro-LED arrays on flexible substrates

Micro‐Light Emitting Diode: From Chips to Applications

“…[ 55 ] Further, simulation showed that for flexible micro‐LED displays, the heat decayed efficiently when the LEDs were in direct contact with metallic pads (Cu) [polyimide (PI)/Cu (150 µm/100 nm) and PI/Cu (150/1 µm)] substrates. [ 56 ] Similarly use of flexible AnSn film substrates allowed much higher current densities for vertical LEDs than those mounted on polyethylene terephthalate due to the ≈300 W m −1 K −1 increase in thermal conductivity. [ 57 ] In addition, due to diamond's superior thermal conductivity properties ( k = 2200 W m −1 K −1 ), micro‐LED on‐diamond was shown to sustain current densities up to 790 W cm −2 without any thermal roll‐over.…”

Enhanced Photoresponse Performance of Self‐Powered PTAA/GaN Microwire Heterojunction Ultraviolet Photodetector Based on Piezo‐Phototronic Effect

“…What's more, it is resistant to high temperature, strong radiation, and has higher chemical stability, is widely used in harsh working environments. [15][16][17][18] Until now, different kinds of GaN-based self-powered PDs have been reported, [19][20][21][22][23] in which the organic/inorganic hybrid selfpowered PDs have gained tremendous research interest because of their unique properties combining the excellent intrinsic carrier mobility of inorganic materials and the abundant merits of organic components with tunable functionality, easy of fabrication, low cost and high flexibility. [24][25][26][27][28][29] Among various organic materials, PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl) amine]) is a typical π-electron conjugated polymer with a high hole transport rate (10 -3 up to 10 -2 cm 2 V -1 s -1 ), which has been widely applied in perovskite solar cells, polymeric light emitting diodes and organic field effect transistors owing to its good film-forming characteristic, nonwetting surface, transparency, and high stability, [30][31][32] thus may be a good choice in UV PDs.…”

Heat Dissipation in Flexible Nitride Nanowire Light-Emitting Diodes

“…The fabrication of flexible devices from conventional thin-film structures requires additional processing steps to lift-off and microstructure the active layer. To simplify the process, alternative fabrication routes were actively explored based on nanomaterials such as bottom-up nanowires (NWs) [4][5][6][7][8][9][10][11][12][13]. NWs not only have remarkable optoelectronic properties, but they can also withstand high deformations without plastic relaxation [14,15].…”

“…NWs not only have remarkable optoelectronic properties, but they can also withstand high deformations without plastic relaxation [14,15]. These properties motivated the intense research of NW flexible LEDs [4,[8][9][10][11][12][13]16]. In most realizations, NWs are embedded in a transparent polymer (e.g., polydimethylsiloxane (PDMS), polyimide, SU-8, or parylene [12,[17][18][19][20][21]), which acts as a supporting material to form the active membrane.…”

“…While III-V material composing NWs has a long lifetime and can withstand high temperatures, the embedding polymer is prone to degradation. Additionally, polymers are characterized by poor thermal conductivity (~1.5 W m −1 K −1 for PDMS [13] compared with~200 W m −1 K −1 for GaN [22]), so self-heating issues can be severe in NW/polymer composite membranes. Therefore, one can question the flexible NW LEDs' ability to operate at high current.…”