The role of acoustic phonon scattering in charge transport in organic semiconductors:a first-principles deformation-potential study  

作　　者：TANG Ling LONG MengQiu WANG Dong SHUAI ZhiGang 

机构地区：[1]Department of Chemistry,Tsinghua University,Beijing 100084,China [2]Key Laboratory of Organic Solids,Beijing National Laboratory for Molecular Science,Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190,China

出　　处：《Science China Chemistry》2009年第10期1646-1652,共7页中国科学（化学英文版）

基　　金：Supported by the Ministry of Science and Technology of China (Grant Nos. 2006CB806200, 2006CB932100, and 2009CB623600);the National Natural Science Foundation of China (Grant No. 20833004)

摘　　要：The electron-acoustic phonon scattering for charge transport in organic semiconductors has been studied by first-principles density functional theory and the Boltzmann transport equation with relaxation time approximation. Within the framework of deformation-potential theory, the electron-longitudinal acoustic phonon scattering probability and the corresponding relaxation time have been obtained for oligoacene single crystals (naphthalene, anthracene, tetracene and pentacene). Previously, the electron-optic phonon scattering mechanism has been investigated through Holstein-Peierls model coupled with DFT calculations for naphthalene. Numerical results indicate that the acoustic phonon scattering intensity is about 3 times as large as that for the optic phonon and the obtained mobility is in much better agreement with the result of the experiment done for ultrapure single crystals. It is thus concluded that for closely packed molecular crystal where the electron is partly delocalized, acoustic phonon scattering mechanism prevails in the charge transport. Moreover, it is found that the intrinsic electron mobility is even larger than hole mobility. A frontier orbital overlap analysis can well rationalize such behavior.The electron-acoustic phonon scattering for charge transport in organic semiconductors has been studied by first-principles density functional theory and the Boltzmann transport equation with relaxation time approximation. Within the framework of deformation-potential theory, the electron-longitudinal acoustic phonon scattering probability and the corresponding relaxation time have been obtained for oligoacene single crystals (naphthalene, anthracene, tetracene and pentacene). Previously, the electron-optic phonon scattering mechanism has been investigated through Holstein-Peierls model coupled with DFT calculations for naphthalene. Numerical results indicate that the acoustic phonon scattering intensity is about 3 times as large as that for the optic phonon and the obtained mobility is in much better agreement with the result of the experiment done for ultrapure single crystals. It is thus concluded that for closely packed molecular crystal where the electron is partly delocalized, acoustic phonon scattering mechanism prevails in the charge transport. Moreover, it is found that the intrinsic electron mobility is even larger than hole mobility. A frontier orbital overlap analysis can well rationalize such behavior.

关 键 词：MOBILITY acoustic PHONON SCATTERING BOLTZMANN equation ORGANIC materials 

分 类 号：O621.13[理学—有机化学]