Liquid organic semiconductor material

Abstract

An organic material having at least one aromatic conjugated π-electron system is selected. The purity of the organic material is improved by purification, and a conduction mechanism of the organic material is confirmed by a time-of-flight method, whereby a liquid phase of the organic material is usable as an organic semiconductor. A method that enables the usage of a liquid phase of an organic material as an organic semiconductor is provided. The method involves confirming the electronic conduction of the organic material having at least one aromatic conjugated π-electron system by evaluation of a charge transport property using a time-of-flight method, and by evaluation of a dilution effect caused by addition of a diluent.

1 . A method for measuring characteristics of an organic substance, comprising:
 (a) disposing the organic substance to be measured between a pair of electrodes;   (b) injecting charges into the organic substance and measuring a transient current in an isotropic liquid phase of the organic substance using a time-of-flight method;   (c) separating the transient current into a current by electronic conduction and a current by ionic conduction; and   (d) measuring a charge amount corresponding to each separated current,   wherein purity of the organic substance is evaluated based on the charge amount corresponding to each separated current.   
     
     
         2 . The method according to  claim 1 , wherein the charge injection into the organic substance is conducted by applying a pulse voltage or a pulse light to the organic substance. 
     
     
         3 . The method according to  claim 1 , wherein the organic substance is purified to the extent that the organic substance exhibits electron conduction and/or hole conduction. 
     
     
         4 . The method according to  claim 1 , wherein the organic substance is an organic semiconductor material, and a semiconductor property of the organic semiconductor material is evaluated based on the charge amount corresponding to each separated current. 
     
     
         5 . The method according to  claim 4 , wherein the semiconductor property is purity of the organic semiconductor material as an electronic material, wherein the purity of the organic semiconductor material as an electronic material is relative concentration of a substance serving as an electronic trap. 
     
     
         6 . The method according to  claim 4 , wherein the semiconductor property is mobility, and whether the conduction mechanism, in the organic semiconductor material, is electronic conduction or ionic conduction is determined based on a value of mobility measured. 
     
     
         7 . The method according to  claim 6 , wherein when the mobility measured ismobility of 10 −3  cm 2 /Vs, the conduction in the organic semiconductor material is evaluated as electronic conduction. 
     
     
         8 . The method according to  claim 6  or  7 , wherein whether the conduction mechanism is electronic conduction or ionic conduction is determined based on a change in the mobility due to a change in viscosity of the organic substance or a change in an intermolecular distance of the organic substance between before and after adding a diluent. 
     
     
         9 . The method according to  claim 8 , wherein the diluent is a substance having HOMO and LUMO levels, the HOMO and LUMO levels being not providing an electronic trap level with respect to HOMO and LUMO levels of the organic substance. 
     
     
         10 . The method according to  claim 1 , wherein the organic substance is a mixture. 
     
     
         11 . The method according to  claim 10 , wherein the organic substance is in the form of solution. 
     
     
         12 . The method according to  claim 1 , wherein the pair of electrodes are respectively disposed on a pair of substrates, and a charge injection means for injecting charges into the organic substance is provided. 
     
     
         13 . The method according to  claim 12 , wherein the pair of substrates, the pair of electrodes and the charge injection means form a cell for measuring electronic conduction and/or ionic conduction.