Method for measuring carrier mobility of organic semiconductor by using evanescent wave as excitation source

Abstract

The invention relates to a method for measuring the mobility of an organic semiconductor material current carrier by utilizing an evanescent wave generated by a total internal reflection method as an excitation source. The method comprises the steps that: firstly, an organic semiconductor material film with thickness d is prepared on a semitransparent electrode and the vapor deposition of a layer of metal electrode is carried out; later, pulsed light is led to the surface of the semitransparent electrode by incidence at the angle that Theta<1> is more than or equal to Theta <c> and less than or equal to 90 DEG, the evanescent wave generated by the total internal reflection generates a hole-electron pair in the organic semiconductor material film; the hole or the electron carries out drift motion toward a cathode or an anode under the action of an electric field formed by externally applied voltage U and finally collected by the cathode or the anode, and a transient photocurrent is collected by a signal collection part, thus determining the time t for the hole or the electron to transit across the organic semiconductor material film and then obtaining the mobility of the organic semiconductor material current carrier, namely, Mu equals to d<2> divided by Ut. The method can control the generation quantity of photon-generated carriers by adjusting the lightness of the exciting light, thus improving the measurement accuracy of the mobility of the current carriers.

Description

technical field [0001] The invention belongs to the technical field of carrier mobility testing of organic semiconductor materials, and in particular relates to a method for measuring carrier mobility of organic semiconductor materials by using evanescent waves generated by a total internal reflection method as an excitation source. technical background [0002] Organic semiconductor materials are widely used in optoelectronic devices such as light-emitting diodes, solar cells, and field-effect transistors due to their advantages such as easy regulation of molecular structure, simple preparation process, and large-area flexible devices. Carrier mobility (usually represented by .) is an important basic parameter of organic semiconductor materials, and is closely related to the performance of organic semiconductor optoelectronic devices. Carrier mobility is defined as the ratio of the average drift velocity V of free carriers (electrons or holes) to the applied electric field ...

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Problems solved by technology

Although the thickness of the excitation layer can be controlled to a certain extent by adjusting the intensity of the excitation light source, it is very imprecise, and the thickness of the thin layer of photogenerated carriers is difficult to measure; at the same time, in order to minimize the thickness of the excitation thin layer, it is necessary to reduce the current the number of generated carriers, thus causing great difficulty in obtaining accurate and reliable carrier mobility

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