摘要
用改进的Ｎａａｒｍａｎｎ方法制备出高质量聚乙炔膜，作碘和四氯化铁重掺杂。用扫描电镜观察到样品纤维间的接触，在链间产生接触势垒，形成隧穿结。反式聚乙炔在重掺杂时会出现孤子晶格，在能隙中央形成孤子能带。在热激活下，带电孤子中的电子即会跳入附近的中性孤子。这有利于孤子能带中的电子，通过能带中接力式的跳跃，进入导带，成为自由电子。电子的这种跳跃会在结的两端引起电压涨落，促使电子参予隧穿导电。从反式聚乙炔的哈密顿量出发，导出了热涨落电压ＶＴ所引起的电压涨落几率Ｐ（ＶＴ）。然后利用涨落诱导隧穿导电理论和有效介质理论，获得样品的直流电导率公式。测量了样品的直流电导率随温度的变化关系。
By use of a modified Naarmann′s method, the good quality polyacetylene films were synthesized. The films were doped highly with iodine and iron chloride. Taking advantage of a scanning electron microscope, contacts between fibres in the sample were observed. At the contact of two fibres, it was produced a contact potential barrier between two mutual contact polyacetylene chains of respective fibres, and formed a small tunnel junction. Because the soliton lattice should be emerged in trans polyacetylene when it is highly doped, the soliton level which in the middle of the energy gap would extend to form a soliton band. Under the thermal activation, electrons of charged solitons in the band can jump into nearby neutral solitons. It is advantageous for electrons in the soliton band to make use of the relaying type of jumps, pass through the soliton band, hop into the conduction band, and become free. These jumping electrons can produce thermally activated voltage fluctuations across junctions that impel free electrons to participate in the tunneling conduction. In view of this, the voltage fluctuation probability P(V T) raised by the thermal fluctuation voltage V T, on the one hand, is proportional to the thermal activation probability ω r of electrons, and on the other hand is proportional to the square root of the number of neutral solitons n 1/2 s in the soliton band, that is P(V T)∝ ω r· n 1/2 s. From the Hamiltonin of trans polyacetylene, ω r was calculated, and from the electronic state density formula and the distribution function in the soliton band, n 1/2 s was computed, then the probability function P(V T) was derived. By use of the fluctuation induced tunneling conduction theory, the conductivity formula of a single tunnel junction of trans polyacetylene was obtained. In light of the effective medium theory, the dc conductivity formula of the sample was achieved. the temperature dependence of dc conduc
出处
《高分子材料科学与工程》
EI
CAS
CSCD
北大核心
1998年第5期99-102,共4页
Polymer Materials Science & Engineering
基金
国家自然科学基金
关键词
反式
聚乙炔
重掺杂
导电
半导体
trans polyacetylene, highly doped samples, soliton lattice, theory of fluctuation induced tunneling conduction
