The Study Of Amino Acids Absorbed Onthe Surface Of Metal Oxides And Its Application In Devices

As one kind of new photovoltaic technology, organic optoelectronic devices are appearing in human research which mainly use organic semiconductor materials to harvest sunlight. At present, organic optoelectronic devices research mainly focuses on the design of donor and acceptor materials, modification of the electrode interface and project of device structure. This paper mainly studied the effect of electrode interface modification in organic optoelectronic devices and proposed a new type of small biological molecule as interface modification. Amino acids were used to modify ITO sheet. A relation was set up between biomaterials and organic optoelectronic devices. The main research contents including:Amino acids were formed on titanium dioxide(Ti O2)nanofibers and nanoparticles substrates by self-assembled monolayer method. Chemical bonds of amino acids were charactered by the Fourier Transform Infrared Spectroscopy and Surface Enhanced Raman Scattering. Although the gap between Ti O2 nanofibers is large, functional group signals of arginine can also be characterized by Raman spectra, which indicates that the electromagnetic enhancement mechanism is not main reason for the enhanced Raman signals of arginine. In the FTIR spectra of arginine that absorbed on Ti O2 nanoparticles, the wavenumber of COO- symmetric stretching vibration shifted from 1376 cm-1 to 1379 cm-1, and the COO- antisymmetric stretching vibration shifted from 1556 cm-1 to 1589 cm-1, which result in the difference between antisymmetric stretching vibration and symmetric stretching vibration is bigger than 200 cm-1. Therefore, the coordination mode between COO- of arginine and Ti O2 nanoparticles is monodentate ligand. In Surface Enhanced Raman Scattering spectra, the shift of COO- symmetric stretching vibration and antisymmetric stretching vibration can also indicate that carboxyl(-COOH)of arginine can react with the hydroxyl(-OH)on the Ti O2 surface.In organic optoelectronic devices, amino acids were employed as modified layer to modify ITO cathode. Through optimizing the p H value of the amino acids, the organic solar cell with asparagine(p H = 4.5)as modified layer exhibited excellent performance: Jsc=12.84, Voc=0.56 V, and PCE=3.69%, while without modified layer exhibited poor performance. And the diode characteristic was also improved. With amino acids modification, the work function of ITO surface was reduced through the analysis of Ultraviolet Photoelectron Spectroscopy. In this situation, the ITO can match with the LUMO levels of acceptor well, allowing more carrier flow to external circuit per unit time. In addition, we discuss two kinds of organic photodetectors(OPDs)modified with amino acids. The ultraviolet-visible OPDs with arginine modification exhibited detectivity up to 1012 Jones at 400-600 nm. The near infrared OPDs with arginine modification had a wide band response from visible light to near-infrared light(400-800 nm)and exhibited a highest detectivity up to 2.36×1013 Jones at 780 nm under 0 V, along with a fast response speed and long time stability.