Hybrid organic-inorganic perovskite (HOIP) is a promising semiconductor for optoelectronic devices. Here, we first introduce a HOIP metasurface to enhance light absorption and boost photocurrent by more than ten times in the frequency ranging from ultraviolet to visible. Based on the HOIP metasurface, a broadband photodetector is realized. Then with a chiral perovskite metasurface, we achieve a multi-polarization-sensitive photodetector, which is sensitive to both linear and circular polarized light simultaneously. Further we develop a flexible and ultra-thin HOIP photodetector. For the application demo, the photodetector has been applied as a signal receiver for transmitting messages in broadband optical communication.
Flexible optoelectronic devices attract considerable attention due to their prominent role in creating novel wearable apparatus for bionics, robotics, health care, and so forth. Although bulk single-crystalline perovskite-based materials are well-recognized for the high photoelectric conversion efficiency than the polycrystalline ones, their stiff and brittle nature unfortunately prohibits their application for flexible devices. Here, we introduce ultrathin single-crystalline perovskite film as the active layer and demonstrate a high-performance flexible photodetector with prevailing bending reliability. With a much reduced thickness of 20 nm, the photodetector made of this ultrathin film can achieve a responsivity much higher than that of recently reported flexible perovskite photodetectors. The demonstrated 0.2 MHz 3 dB bandwidth further paves the way for high-speed photodetection.
In this work, we intentionally explored the heavily p-doped graphene stacks by degenerate femtosecond pump-probe spectroscopy, and observed an excitation enhancement of hot electrons at weak pump fluence. Physically, both Auger processes and population inversion are suppressed in this system, yet it becomes possible for the conduction bands to be effectively evacuated within the pulse duration through the ultrafast cooling of hot electrons, which may lead to an enhanced excitation of hot electrons. This excitation enhancement can be further strengthened by multiple layer-stacking processes or a thermal annealing pretreatment. Furthermore, large modulation depth is achieved in graphene stacks with small variation of pump fluence. We suggest that this effect can have potential applications on harvesting energy from excited hot electrons, and may provide a unique way to achieve high-speed modulators, photodetectors, solar cells, and photocatalysts.
Dielectric metamaterials with high refractive indices may have an incredible capability to manipulate the phase, amplitude, and polarization of the incident light. Combining the high refractive index and the excellent electrical characteristics of the hybrid organicinorganic perovskites (HOIPs), we demonstrate that metamaterial made of HOIPs can trap visible light and realize effective photonto-electron conversion. The HOIP metamaterials are fabricated by focused ion beam milling on a solution-grown single-crystalline HOIP film. The optical absorption is significantly enhanced at the visible regime compared to that of the flat HOIP film, which originates from the excited Mie resonances and transverse cavity modes with inhibited interface reflection. Our results point to the potential application of HOIP metamaterials for high-efficiency light trapping and photon-to-electron conversion.
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