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Despite the fascinating optoelectronic properties of graphene, the power conversion efficiency (PCE) of graphene based solar cells remains to be lifted up. Herein, it is experimentally shown that the graphene/quantum wells/GaAs heterostructure solar cell can reach a PCE of 20.2% and an open‐circuit voltage (Voc) as high as 1.16 V at 90 K. The high efficiency is a result of carrier multiplication (CM) effect of graphene in the graphene/GaAs heterostructure. Especially, the external quantum efficiency (EQE) in the ultraviolet wavelength can be improved up to 72.2% based on the heterostructure constructed by graphene/In0.15Ga0.85As/GaAs0.75P0.25 quantum wells/GaAs. The EQE increases as the light wavelength decreases, which indicates more carriers can be effectively excited by the higher energy photons through CM effect. Owing to these physical characters, the graphene/GaAs heterostructure solar cell will provide a possible way to exceed Shockley–Queisser (S–Q) limit. [ABSTRACT FROM AUTHOR]

The graphene/water/semiconductor structure can convert kinetic energy into direct current output using the polarization principle, showing its unique physical characteristics and superior performance in the power generation direction. Herein, a photodetector application is developed based on the structure and reveals the physical mechanism of the displacement current caused by the polarization of more water molecules induced by silicon upon excitation under illumination. Furthermore, the research uses a graphene/water/silicon heterojunction as a self‐driven photodetector with a wide response band contains from ultraviolet to visible light, the photodetector has a high sensitivity to the incident light of 635 nm with a responsivity of 433.46 mA W−1 and detectivity as 1.57 × 1012 Jones. Moreover, the photodetector based on graphene–water–Si has an ultrafast response speed, with a typical rise/fall time of 564/766 ns. The photodetector remains substantial stable while sealed with polymethyl methacrylate after storage in air for 1 month. These results imply that graphene/water/silicon heterojunctions may have great potential for practical applications as high‐performance self‐driven photodetectors. [ABSTRACT FROM AUTHOR]

Dynamic semiconductor diode generators (DDGs) offer a potential portable and miniaturized energy source, with the advantages of high current density, low internal impedance, and independence of the rectification circuit. However, the output voltage of DDGs is generally as low as 0.1–1 V, owing to energy loss during carrier transport and inefficient carrier collection, which requires further optimization and a deeper understanding of semiconductor physical properties. Therefore, this study proposes a vertical graphene/silicon DDG to regulate the performance by realizing hot carrier transport and collection. With instant contact and separation of the graphene and silicon, hot carriers are generated by the rebounding process of built‐in electric fields in dynamic graphene/silicon diodes, which can be collected within the ultralong hot electron lifetime of graphene. In particular, monolayer graphene/silicon DDG outputs a high voltage of 6.1 V as result of ultrafast carrier transport between the monolayer graphene and silicon. Furthermore, a high current of 235.6 nA is generated due to the carrier multiplication in graphene. A voltage of 17.5 V is achieved under series connection, indicating the potential to supply electronic systems through integration design. The graphene/silicon DDG has applications as an in situ energy source for harvesting mechanical energy from the environment. [ABSTRACT FROM AUTHOR]

The exploration of two-dimensional (2D) materials in highly performance optoelectronic device is critical for the practical applications. Traditionally, GaN related semiconductors uses complicated multiple quantum wells to increase the overlap of electron and hole waves for highly efficient light emitting diode (LED). In this work, through designing the Graphene/MoS 2 heterostructure for increasing the hot electron lifetime and subsequently enhancing the process of carrier multiplication (CM), we successfully realize the highly efficient Graphene/MoS 2 /p-GaN LED with external quantum efficiencies (EQE) of 15.89% under 0.625 mA/mm2. Compared with the Graphene/p-GaN LED device, the addition of MoS 2 leads to stronger light output and the maximum EQE increased by 61%. The energy bands alignment between MoS 2 and GaN squeezes the hole at the MoS 2 layer, when the numbers of holes are increased by graphene as a result of CM effect, which recombines with electron at the surface of GaN defects resulting in the strong light output at reversed bias. We believe that this work will bring a brand new insight of realizing high efficient 2D materials based LED and optoelectronic devices. [Display omitted] • We successfully realize hot carriers assisted mixed-dimensional Graphene/MoS 2 /p-GaN LED. • The CM effect in the Graphene effectively increases the accumulation of carriers at the junction area between the MoS 2 and p-GaN. • The radiative recombination on the surface of p-GaN improve the EQE. [ABSTRACT FROM AUTHOR]