有机半导体的物理掺杂理论

摘要: 基于最低未被占据分子轨道(LUMO)和最高被占据分子轨道(HOMO)的高斯态密度分布与载流子在允许量子态中的费米.狄拉克(Fermi-Dirac)分布,提出有机半导体中物理掺杂的理论模型;研究了掺杂浓度、温度和禁带宽度对载流子浓度的影响,并与一些报道的实验结果做了比较.研究发现无论是否掺杂,温度升高时,有机半导体中的载流子浓度都会增大,并且随温度倒数的线性减小而指数增大;对于本征有机半导体,载流子浓度随禁带宽度的增大而指数下降,随高斯分布宽度的平方指数增加;对杂质和主体不同能级关系的掺杂情形下掺杂浓度对载流子浓度的影响做了数值研究.

关键词:

Abstract: A theory for carrier concentration in physically doped organic semiconductors has been presented based on Gaussian energy distribution of the lowest unoccupied molecular orbitals (LUMOs) and the highest occupied molecular orbitals (HOMOs) as well as the Fermi-Dirac distribution of carriers in allowed quantum states. The dependence of carrier concentration on doping concentration, ambient temperature and energy gap of organic semiconductors were numerically investigated. It is shown that carrier concentration will increase with the ambient temperature in doped or undoped organic semiconductors, and the carrier concentration decreases exponentially with the reciprocal of temperature. For intrinsic organic semiconductor, carrier concentration will decrease exponentially with the energy gap (the difference between the average energy levels of HOMO and LUMO)and increase exponentially with the square of the width of Gaussian distribution. We then discussed the effect of doping concentration on carrier concentration for different HOMO and LUMO positions of the dopant relative to that of the host.

有机半导体的物理掺杂理论

关键词:

The theory of physical doping in organic semiconductor

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