Photoelectric Properties Of Graphene And Two-Dimensional Perovskite Nanosheets And Their Photonic Applications

Photoelectronic devices based on the photons as information carriers,play an increasingly important role in the development of modern information technology.A photoelectronic circuits include light emitting devices,modulator and receiving devices.such as light-emitting diode.laser,optical filters,optical modulator,photodetector,etc.Graphene with exceptionally physical,chemical,and electronic quality,has already gained widely attention and revealed a cornucopia of new physics and potential applications,such as photodetectors,photovoltaic devices,optical modulation,laser optoelectronics and other fields.Recently,two-dimensional organic and inorganic perovskite materials show the combined property of both two-dimension and bulk materials,which exhibits outstanding photoelectric properties.This project would be of great significant for the development and application of two-dimensional materials.In this research,it focuses on the photoelectric properties of graphene and two-dimensional perovskite nanosheets with their photonic applications,including the mode-locked laser,optical waveguide,photodetector and field of photovoltaic.The special projects and innovations are as following:1.A large area of high quality monolayer graphene films are prepared by chemical vapor deposition method.The graphene-based thin films are successfully applied as transparent conductive electrode.The performance of graphene-based thin films can be improved by doping with HNO3.A combined solution process and vapor-phase conversion method is used to synthesize 2D hybrid organic-inorganic perovskite(CH3NH3PbI3)nanocrystals.High-quality 2D perovskite crystals can be achieved on different substrate.2.2D perovskite nanosheets are successfully prepared by a combined solution process and vapour phase conversion method.It is found that 2D perovskite nanosheets have stronger saturable absorption properties with large modulation depth and very low saturation intensity compared with bulk perovskite films.Using an all dry transfer method,I construct a new type of saturable absorber device based on single piece of 2D perovskite nanosheet.Stable soliton state mode-locking is achieved and ultrafast picosecond pulses were generated at 1064 nm.This work is likely to pave the way for ultrafast photonic and optoelectronic applications based on 2D perovskites.3.A silicon ring resonators modulator concept based upon a graphene layer is presented.Graphene acts as a tunable absorber,effectively reducing the noise of output optical signal and the 3dB bandwidth.The effect of background doping and potential fluctuations on the bandwidth,modulation depth and insertion loss are also quantified.4.The fabrication of a novel hybrid photodetector consisting of graphene and 2D perovskite nanosheets are demonstrated,which is produced by a combined solution process and vapor-phase conversion method.Firstly,high-quality 2D perovskite nanosheets as thin as a single unit cell are grown and demonstrated as visible photodetector.Secondly,high-performance photodetector based on graphene-perovskite heterostructure has been introduced.Finally,perovskite-based flexible photodetector is also demonstrated based on this simple structure.This graphene-perovskite heterostructure are very promising for highly efficient,flexible and low cost broadband photodetectors for optoelectronics applications.