Spintronic Study Based On Soluble Organic Semiconductors

Soluble organic semiconductors are the primary research direction in organic electronics study.The preparation of room-temperature(RT)operable organic spin valves based on soluble semiconductors is the important content and development tendency during the research of organic spintronics and has attracted widely attentions in the world.The realization of this target has a close correlation with the fabrication technology of reliable spin valves,the improvement of spin injection efficiency,and the optimization of spin transport characterization of organic semiconductor layer.In this paper,firstly,we solve the penetration problem via equipment upgrading,and then improve spin injection efficiency by optimizing the interface between electrode and organic layer.Finally,through the solvent screening and annealing condition optimization,we successfully prepare RT operable spin valves based on spin-coating PCE10 and PC₇₁BM semiconductors,respectively.Moreover,we research their RT spin transport properties and photovoltaic effects.In addition,with respect to the equipment limitation during preparing reliable spin valves,we develop a novel method for preparing reliable organic spin valves,which will not be restricted by the equipment and it is very simple and universal.The major research works contained four aspects are generalized as follows:(1)Optimization of device fabrication equipment and spin injection interlayer.The penetration problem has been solved by upgrading the substrate table in traditional e-beam evaporation equipment with adding liquid nitrogen rotation system.At the meanwhile,the spin injection efficiency has been improved by optimizing the thickness and oxidizing condition of spin injection interlayer,leaky-Al O_x.These strategies lay an important foundation for preparing RT operable spin valve based on solution method.(2)Preparing RT spin valve based on P-type semiconductor.Based on the development of device preparing technology,as well as solvent screening and annealing condition optimizing,we first successfully fabricate a RT operable spin valve with spin-coating P-type polymer semiconductor,PCE10.A RT spin valve effect of up to 4.7%and a transport distance of spin-polarized hole of 37 nm have been obtained.(3)Preparing RT spin photovoltaic device based on N-type semiconductor.We are the first group to successfully prepare a RT operable spin-photovoltaic device based on spin-coating N-type small-molecule semiconductor of PC₇₁BM,and the RT spin transport distance exceeds 55 nm.By modulating the thickness of PC₇₁BM layer,a spin valve with both spin valve effect and strong photovoltaic effect is obtained.By the modulation of light intensity and applied bias,the output current and completely spin-polarized current can be modulated at RT,moreover,an infinitely-great magnetocurrent(MC)value can be obtained.(4)Developing a novel method for preparing spin devices.Utilizing the well film-forming property of polystyrene(PS)solution on octadecyltrichlorosilane(OTS)self-assembly membrane(SAMs)and the non-stick property between PS and SAMs thin film,we successfully develop a method called“polymer-based top electrode transferring method”for preparing organic spin valves.It is water and oxygen isolation,equipment independent,and has shown simple and universal advantages.The reliability of this spin valve is verified by cross-section TEM image,EDS image and RT spin valve effect of4.5%.