复合阴极缓冲层Alq_3∶CsF对CuPc/C_(60)电池性能的影响

通过Alq_3∶CsF复合阴极缓冲层来优化CuPc/C_(60)有机小分子太阳能电池的性能。当Alq_3∶CsF厚度为5nm,CsF的掺杂比例为4%时,加入复合阴极缓冲层器件较Alq_3阴极缓冲层器件的能量转化效率提高了49%,到达0.76%,并且在室温、大气的条件下,器件的稳定性也得到了保持,与未加阴极缓冲层的器件相比,半衰期提高了6倍,达到9.8h。通过紫外-可见吸收、外量子效率和单载流子传输器件等研究了器件效率改善的主要原因是掺入CsF后,调节界面能级,改善了Alq_3的电子传输特性,提高了器件的短路电流和填充因子。比较分析复合阴极缓冲层器件于空气中放置不同的时间的电流电压曲线,表明Alq_3∶CsF可以保持Alq_3的良好稳定性,可以很好地阻挡氧气与水分的扩散,提高器件的寿命。     

石墨炉原子吸收光谱法直接测定城市污泥中有机态镉

建立了真空冷冻干燥法制备有机相标准系列,氯化钯-磷酸氢二钾作基体改进剂,分步斜坡升温石墨炉原子吸收光谱法直接测定城市污泥中痕量有机态Cd的方法,有效地消除了基体干扰.方法的精密度(RSD,n=11)为5.7%,用于污泥样品的测定加标回收率在91%-107%之间,与常规消解法测定值比较结果令人满意.     

引入阱结构改善有机发光器件的效率

利用阱结构作为发光层,阱由8-羟基喹啉铝和 4,4′-N,N′–dicarbazole-biphenyl交替蒸发长成,改善了器件的效率,这归因于增加空穴和电子在薄发光层的堆积,形成的激子有效地被限制在薄的发光层中发光.器件的最大电流效率在外加电压8V时达到4.1cd/A,与一般异质结器件相比效率提高了2倍多.这说明在适当阱数时用简单办法可提高器件的效率.     

Dynamic barrier height modulation analysis of metal-insulator-semiconductor junctions built on silicon surfaces modified by covalent organic layers

Aim of this paper is to validate a modified Schottky barrier model accounting for the electrical properties of metal - self-assembled layer - semiconductor structures. To this end, the effect of the dynamic modulation of the dipole moment of the organic layer was studied. The system was a junction built on Si(1 0 0) surfaces modified by grafting an organic layer by wet chemistry reactions. As the metallic electrode, a thin, porous gold layer was deposited, enabling gas diffusion through it. In such a geometry, a polar gas was allowed to adsorb onto the Si surface, and the variation of the barrier height could be measured and correlated with the dipole moment of the gas molecule and its partial pressure.     

Mechanism of two-dimensional chiral growth of 6,13-pentacenequinone thin films on Si(1 1 1)

Thin film growth of 6,13-pentacenequinone (C₂₄H₁₂O₂, PnQ) on Si(1 1 1)-7 × 7 at room temperature (RT) was studied by low-energy electron microscopy (LEEM) and ab initio density functional theory (DFT) calculations. Our experiments yielded direct microscopic observation of enantiomorphic evolution mechanism in the initial stage of the chiral-like growth of PnQ islands, under kinetic growth conditions. We observed that the faster growth direction aligns with the direction of easier molecule incorporation, or lowest kink formation energy, rather than along the lowest energy step. Real time observation of the growth and subsequent relaxation of island shape revealed that kinetically stiff direction differs from the thermodynamic one. This feature together with anisotropic mass incorporation determines the enantiomorphic evolution and rotational arrangement of crystallites during the growth of elongated organic molecules, like PnQ.     

Influence of the deposition temperature on the structure and performance of tris(8-hydroxyquinoline) aluminum based flexible organic light-emitting devices

Based on indium tin oxide (ITO)/N,N′diphenyl-N-N′-di(m-tdyl) benzidine (TPD)/Alq₃/Al structure, flexible OLEDs on polyethylene terephthalate (PET) substrates were fabricated by physical vapor deposition (PVD) method. Tris(8-hydroxyquinoline)aluminum (Alq₃) films were deposited at 90, 120 and 150 °C to examine the influence of the deposition temperature on the structure and performance of OLEDs. Electroluminescence (EL) spectra and current-voltage-luminance (I-V-L) characteristics of the OLEDs were examined. It was found that the device fabricated at a high temperature had a higher external efficiency and longer lifetime. Atomic force microscope (AFM) was adopted to characterize the surface morphology of ITO/TPD/Alq₃. The higher uniform morphology of the Alq₃ formed at high temperature might contribute to the performance improvement of the OLEDs.     

双腔热解光腔衰荡光谱仪测量大气中NO2和RNO2

A two-channel thermal dissociation cavity ring down spectroscopy (CRDS) instrument has been built for in situ, real-time measurement of NO₂ and total RNO₂ (peroxy nitrates and alkyl nitrates) in ambient air, with a NO₂ detection limit of 0.10 ppbv at 1 s. A 6-day long measurement was conducted at urban site of Hefei by using the CRDS instrument with a time resolution of 3 s. A commercial molybdenum converted chemiluminescence (Mo-CL) instrument was also used for comparison. The average RNO₂ concentration in the 6 days was measured to be 1.94 ppbv. The Mo-CL instrument overestimated the NO₂ concentration by a bias of +1.69 ppbv in average, for the reason that it cannot distinguish RNO₂ from NO₂. The relative bias could be over 100% during the afternoon hours when NO₂ was low but RNO₂ was high.     

Temperature dependent polariton emission from strongly coupled organic semiconductor microcavities

We investigated the absorption and photoluminescence (PL) of J-aggregates of a cyanine dye both in a thin film format and when used as the active layer in a strongly-coupled microcavity. We show that as temperature is reduced, the absorption linewidth of the J-aggregates narrows and shifts to higher energy. When the J-aggregate is placed in a microcavity we find that the energy of the polariton modes also shifts to higher energies as temperature is reduced. We compare the intensity of PL emission from the upper and lower branches at resonance as a function of temperature, and find that it can be described by an activation energy of 25 meV. PL emission spectra at resonance also suggest that uncoupled excitons inside the microcavity populate the upper polariton branch states.     

体异质结有机太阳能电池性能提高的研究

制备了四种不同结构的有机太阳能电池器件,器件1 ITO/LiF/PEDOT∶PSS/MEH-PPV/C₆₀/Al、器件2 ITO/PEDOT∶PSS/MEH-PPV/C₆₀/Al、器件3 ITO/LiF/PEDOT∶PSS/MEH-PPV∶C₆₀/C₆₀/Al和器件4 ITO/PEDOT∶PSS/MEH-PPV∶C₆₀/C₆₀/Al。测量了它们的电流－电压特性,结果显示在ITO和PEDOT∶PSS之间插入一薄层LiF使得器件性能得到较大提高。其器件1的J_SC和FF比器件2的提高了74%和31%; 器件3的J_SC比器件4的提高了约40%。这主要是由于LiF层有效地抑制了空穴向阳极的传输,并且LiF层在ITO和PEDOT:PSS之间形成了良好的界面特性。因此,这种结构上的改进有效地提高了有机太阳能电池的性能。