Thermal annealing effect on organic semiconducting polymer laser with an external holographic grating feedback layer

Thermal annealing effect on an organic distributed feedback (DFB) laser excited from a semiconducting polymer gain layer, poly(2-methoxy-5-(2’-ethyl-hexyloxy)-p-phenyl-envinylene) (MEH-PPV), is reported. The morphology, absorption and photoluminescence (PL) spectral characteristics of the MEH-PPV film annealed at different temperatures were analyzed. The amplified spontaneous emission (ASE), the optical gain and loss coefficients were also investigated. The organic lasing behaviors including threshold, energy conversion efficiency and polarization state in a DFB laser device were studied. The results show that the optical properties of the organic semiconducting laser can be enhanced by thermal annealing effect. The single mode laser emission at 622.4 nm with lower lasing threshold 0.2 μJ/pulse and higher energy conversion efficiency 6.71% was achieved with thermal annealing at 120 °C. The thermal annealing treatment decreases laser threshold and increases laser energy conversion efficiency dramatically, which shows the potential in ultra-low cost organic semiconducting polymer DFB lasers.     

Structural,optical and electrical properties of Li-doped ZnO thin films influenced by annealing temperature

Li-doped Zn O thin films had been grown by radio frequency magnetron sputtering and then annealed under various annealing temperatures. The characteristics of Zn O films were examined by XRD, FESEM, Hall measurement and optical transmission spectra. Results showed that p type conduction was observed in Lidoped Zn O films annealed at 500-600 ℃ and the p type Zn O films possessed a good crystalline with c-axis orientation, dense surface, and average transmission of about 85% in visible spectral region.     

Synthesis and characterization of poly(pyridylurea) and poly(pyridylthiourea), potentially semiconducting polymers

Poly(pyridylureas) and poly(pyridylthioureas) were synthesized by reacting 2,6‐diaminopyridine with phosgene and thiophosgene, respectively, using THF and pyridine as solvent. The synthesized polymers were characterized by IR‐spectroscopy, elemental analysis, and X‐ray photoelectron spectroscopy. Thermal stability of the polymers was determined by thermal degradation between 35°C and 700°C. The 50% weight loss of polypyridylureas was above 400°C while for the polypyridylthioureas it was above 450°C. Undoped poly(pyridylureas) and poly(pyridylthioureas) behave as semiconductors, σ = 10^?9 (Ω cm)^?1. After doping with I₂ and SbF₅, the electrical conductivity increases several orders of magnitude, σ = 10^?7(Ω cm)^?1. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

水热法合成PbTe微晶及其微观形貌表征

采用水热法制备PbTe微晶,研究水热法合成PbTe微晶工艺过程中碲源、反应时间、反应温度、碱加入量、还原剂及表面活性剂等对PbTe微晶形貌的影响,分别采用X射线衍射(X-ray diffraction,XRD)和扫描电镜(scanning electron microscope,SEM)对制备的PbTe进行表征.结果表明,控制不同的合成工艺可制备得到立方体、花状和树突状等多种形貌的PbTe微晶.     

BaO过量的钛酸钡中施主Sb的取代位置

Sb仅在低浓度掺杂时,才能使BaTiO_3半导化。对该现象的解释,先需弄清楚Sb在BaTiO_3晶格中的位置。本文运用缺陷化学理论,分析了Sb掺杂BaTiO_3电导率和氧分压之间的关系,提出BaO过量时,Sb位于BaTiO_3晶格中的Ti位,形成电子补偿,导致BaTiO_3半导化的机理。     

Fabrication and characteristics of porous germanium films

Abstract

Porous germanium films with good adhesion to the substrate were produced by annealing GeO₂ ceramic films in H₂ atmosphere. The reduction of GeO₂ started at the top of a film and resulted in a Ge layer with a highly porous surface. TEM and Raman measurements reveal small Ge crystallites at the top layer and a higher degree of crystallinity at the bottom part of the Ge film; visible photoluminescence was detected from the small crystallites. Porous Ge films exhibit high density of holes (10²⁰ cm^?3) and a maximum of Hall mobility at ～225 K. Their p-type conductivity is dominated by the defect scattering mechanism.     

Synthesis and characterization of polyarylureas. I. Potentially semiconducting polymers

Polyarylureas were synthesized from the reaction between phosgene with aromatic diamines. Depending on the pH, the polyarylureas presented different colors when the solvent used was pyridine. The polyarylureas were characterized by IR spectroscopy, elemental analysis, and X‐ray photoelectron spectroscopy (XPS). To study the thermal stability of the polymers, a thermal degradation was performed between 35 and 700°C. The polyarylureas decomposed above 350°C. Without doping, polyarylureas are considered as semiconductors [σ = 10^?9 (Ωcm)^{? 1}]; after doping with I₂, their electrical conductivity increases by several orders of magnitude. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 822–830, 2001     

Organometallic Conjugated Polymer Networks

Despite the diverse research activities focused on the chemistry, material science and physics of conjugated polymers, the feature of conjugated cross-links, which can provide electronic communication between chains, has received little attention. This situation may reflect the challenge to introduce such cross-links and retain adequate processability. On the basis of selected recent examples, the present review attempts to give a concise overview of the synthesis, processing and electronic properties of the important class of organometallic networks, which are formed through coordination bonds between ligand sites comprised in the organic semiconductor and metallic cross-links. These metallopolymers are also intractable but are often readily accessible via either ligand-exchange reactions or, alternatively, the polymerization of pre-fabricated metal–ligand complexes. If the electronic potentials of the cross-links are tailored to match those of the linear segments, these moieties allow for adequate electronic coupling. An erratum to this article can be found at