Performance Optimization Of Graphene-based Photoelectric Device

Graphene is gifted with several unique physical properties due to its two-dimensional structure.In recent years,the growth process of graphene has been optimized,and high quality mono-layer graphene can be produced in a large scale.Consequently,graphene's excellent conductivity,ductility and good light transmittance have made it widely used in the field of optoelectronic devices,especially in photodetectors and solar cells.In the process of photodetector,the ultra-high carrier mobility of graphene can make the device achieve a great gain,which has great significance for low light detection.Besides,good ductility also spreads the application prospect of graphene in flexible devices.In the process of solar cell,the introduction of graphene can effectively simplify the preparation process and reduce the manufacturing cost while keep the high efficiency at the same time.The research of low cost and high efficiency hybrid cells can bring greater competitiveness to photovoltaic technology.This paper focused on photoelectric devices based on graphene and other semiconductor materials.The basic properties and internal mechanism of Graphene/Silicon(Gr/Si)device and Graphene/Perovskite(Gr/MAPbl3)device were studied to optimize their performance.The obtained results are shown as follow:(1)In the optimization process of Gr/Si photodetectors,Pt nanoparticles(Pt NPs)were applied to induce Localized Surface Plasmon Resonance(LSPR).As a consequence,the absorption of silicon substrate was enhanced.Furthermore,the built-in electrical field between graphene and silicon was also enhanced due to Pt NPs could induce p-type doping to graphene.The detector's minimum detection threshold is lowered from 20 nW to 0.144 nW,and the responsivity can be increased from 1.32×105 A W-1 to 1.68Krl07 A W-1.Meanwhile,Gr/Si photodetectors keep a very fast photoresponse at 180 ns because of low trapped states density at the interface between graphene and silicon.(2)In the optimization process of Gr/MAPbl3 photodetectors,graphene quantum dots(GQDs)were doped into precursor solution of perovskite to enhance the performance of device.Consequently,GQDs could form a bulk heterojunction with perovskites and act as electron trap.Photoelectrons would be trapped at the interface between GQDs and MAPbI3,thus,holes could transfer to adjacent graphene layer with a minimal recombination probability.This mechanism contributed to the responsivity enhancement of Gr/MAPbl3 photodetectors,resulting in a 1.03×l06 AW-1 responsivity.(3)In the optimization process of Gr/Si solar cells,vanadic anhydride(VOx)was inserted into the device as an hole transporting and electron blocking layer.The power conversion efficiency(PCE)was enhanced obviously due to the increase of potential barrier and the decrease of recombination probability.By adjusting the thickness of VOx,one could find the built-in field strengthened little while the VOx layer was very thin,resulting in a low PCE.When it came to a thick layer,both electrons and holes would accumulate at interface,which increased the recombination rate and reduced the PCE.By optimizing the concentration of precursors,we got a PCE promotion from 2.81%to 5.69%.These results show that graphene exhibits great potential in the application of photoelectric devices.