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.

As one of the most important semiconductor materials, silicon (Si) has been widely used in current energy and optoelectronic devices, such as solar cells and photodetectors. However, the traditional Si p–n junction solar cells need complicated fabrication processes, leading to the high cost of Si photovoltaic devices. The wide applications of Si-based photodetectors are also hampered by their low sensitivity to ultraviolet and infrared light. Recently, two-dimensional (2D) layered materials have emerged as a new material system with tremendous potential for future energy and optoelectronic applications. The combination of Si with 2D layered materials represents an innovative approach to construct high-performance optoelectronic devices by harnessing the complementary advantages of both materials. In this review, we summarize the recent advances in 2D layered material/Si heterojunctions and their applications in photovoltaic and optoelectronic devices. Finally, the outlook and challenges of 2D layered material/Si heterojunctions for high-performance device applications are presented.