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Perovskite light‐emitting diodes (PeLEDs) have shown great potential for low‐cost display and lighting technologies, and all‐inorganic blue PeLEDs are recognized as a promising substitute for blue fluorescent/phosphorescent organic light‐emitting diodes (OLEDs) owing to their superior color purity and great stability potential. However, confined by the solution fabrication process, depositing multi‐layered white PeLEDs remains a challenge. Here, a newly designed hybrid perovskite/organic tandem white LED (POTWLED), integrated with a bottom blue PeLED unit and a top orange/(orange + red) OLED unit, to prevent damage to the underlying perovskite layer caused by the deposition of the top emitting layers, is reported. To optimize the performance of POTWLEDs, a conductive passivator of 2,8‐bis(diphenylphosphoryl)dibenzo[b,d] thiophene, with a strong surface binding group of P═O, is introduced to passivate perovskite defects, which promotes a maximum external quantum efficiency (EQE) of 17.3% for blue PeLEDs with an emission peak at 488 nm. As a result, based on the optimized blue PeLED units, a maximum EQE of 23.9% with a low color temperature of 2522 K is obtained for POTWLEDs, which is the highest efficiency for perovskite‐based WLEDs, illustrating the great potential of the hybrid tandem device in fabricating high‐performance perovskite‐based WLEDs. [ABSTRACT FROM AUTHOR]

Hair loss can cause psychological distress. Here, red organic light-emitting diode (OLED) light source is first introduced as the photobiomodulation therapy (PBMT) for hair growth and demonstrated as a promising and non-invasive therapeutic modality for alopecia. OLED exhibits unique advantages of homogeneous irradiation, flexible in form factor, and less heat generation. These features enable OLED to be an ideal candidate for wearable PBMT light sources. A systematic study of using red OLEDs to facilitate hair growth was conducted. The results show that OLEDs excellently promote hair regrowth. OLED irradiation can increase the length of the hair by a factor of 1.5 as compared to the control, and the hair regrowth area is enlarged by over 3 times after 20 days of treatments. Moreover, the mechanism of OLED that stimulates hair follicle regeneration is investigated in-vivo by conducting a systematic controlled experiments on mice with or without OLED PBMT. Based on the comprehensive histological and immunofluorescence staining studies, two key factors are identified for red OLEDs to facilitate hair follicle regeneration: (i) increased autophagy during the anagen phase of the hair growth cycle; (ii) increased blood oxygen content promoted by the accelerated microvascular blood flow. [ABSTRACT FROM AUTHOR]

All-inorganic perovskite light-emitting diodes (AIPeLEDs) have been demonstrated with superior thermal stability than organic analogues, but the high defect density and lattice strain of all-inorganic perovskites commonly result in compromised efficiency and stability of the devices. Herein, a self-assembled molecule, 4-bromobenzoic acid (BBA), is adopted as an additive to modify CsPbBr 3 -based green AIPeLEDs. In particular, the formic acid group (-COOH) of BBA can interact with the uncoordinated Pb dangling bonds, leading to reduced defects and released lattice strain of perovskites, thereby facilitating the formation of all-inorganic perovskite films with a high photoluminescence quantum yield of 54.5 %. As a result, AIPeLEDs with a high maximum current efficiency of 42.4 cd A−1, and an external quantum efficiency of 11.4 % are obtained. Moreover, promoted by the inhibited non-radiative recombination and released lattice stress, the T 50 lifetime (at an initial brightness of 200 cd m−2) is also improved from 2 h for the control PeLEDs to 8 h for the BBA-treated PeLEDs, which further confirms the superiority of BBA in passivating the AIPeLEDs. • A self-assembled molecule (SAM), 4-bromobenzoic acid (BBA), is adopted as an additive to modify all-inorganic perovskite CsPbBr 3 film crystallization properties for the fabrication of green AIPeLEDs. • The interaction between the formic acid group (-COOH) of BBA with the uncoordinated Pb dangling bonds can lead to reduced defects and released lattice strain of perovskites, which promotes a high photoluminescence quantum yield (PLQY) of 54.5 %. • High-performance AIPeLEDs with an external quantum efficiency (EQE) of 11.4 % and a T 50 lifetime (at an initial brightness of 200 cd m−2) of 8 h are obtained. [ABSTRACT FROM AUTHOR]