P3HT/PMMA双层聚合物电双稳器件的研究

通过逐层旋涂的方法,制备了P3HT(poly(3-hexylthiophene))与PMMA(poly(methylmethacrylate))双层器件,并与二者的共混溶液制备的器件进行了性能对比。利用扫描电镜(SEM)表征了双层器件的横截面形貌;利用电流-电压(I-V)以及电流-读取次数(I-t)测试,测量了两种器件的开关比以及持续时间特性。其中,双层器件具有更好的开关比,可达1×10~3,同时反复读写测试表明器件性能非常稳定。为了解释电双稳现象产生的机理,对双层结构器件的电流-电压曲线进行了线性拟合,利用器件的能级图进行分析,得出了电荷在器件中的传输过程。研究结果表明,可以通过电荷俘获释放理论解释P3HT/PMMA双层器件电双稳特性产生的机理。     

基于MEH-PPV/Ir(ppy)_3聚合物电双稳器件

通过逐层旋涂的方法,利用MEH-PPV(Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]与Ir(ppy)_3(tris(2-phenylpyridine)iridium(Ⅲ))),制备活性层,实现了高性能的电双稳器件。通过改变MEHPPV的浓度,制备了不同器件并进行性能比较,发现所有器件都具有明显的电双稳特性。当MEH-PPV的浓度达到4 mg/mL时,器件的开关比可以达10~3。同时,通过测试器件的电流-循环次数研究了器件的持续稳定特性。经过10~4次的反复读写测试,器件性能依然稳定。最后,通过对器件的Ⅰ-Ⅴ曲线进行线性拟合,并结合器件的能级图,对器件的工作原理进行了研究。结果表明,MEH-PPV/Ir(ppy)_3器件的电双稳特性产生的主要原因是偶极层的形成与破坏。     

基于PVP和PbSe三维自组装超晶格复合体系的电双稳器件

采用旋涂工艺将PbSe三维自组装超晶格镶嵌在两层聚合物PVP中,制备了基于PVP和PbSe三维自组装超晶格复合体系的电双稳器件,器件结构为ITO/PVP/PbSe三维自组装超晶格/PVP/Al,研究了其电学性能和记忆效应。与参比器件ITO/PVP/Al相比,器件ITO/PVP/PbSe三维自组装超晶格/PVP/Al的电流-电压特性呈现出非常明显的电双稳特性和非易失记忆行为,在相同的电压下同时具有两种不同的导电状态：低电导的关态和高电导的开态。当PVP与PbSe超晶格的质量比为1：1时,器件性能最好,其最大电流开关比为7×10⁴,经过10⁴ s仍几乎无衰减。通过对电流-电压曲线拟合,利用不同的导电模型对器件的载流子传输机制进行了解释。结果表明,PbSe三维自组装超晶格作为电荷陷阱,可以俘获、储存及释放电荷,对器件的电双稳性能能起决定性作用。     

基于PVP和PbSe三维自组装超晶格复合体系的电双稳器件（英文）

采用旋涂工艺将Pb Se三维自组装超晶格镶嵌在两层聚合物PVP中,制备了基于PVP和Pb Se三维自组装超晶格复合体系的电双稳器件,器件结构为ITO/PVP/Pb Se三维自组装超晶格/PVP/Al,研究了其电学性能和记忆效应。与参比器件ITO/PVP/Al相比,器件ITO/PVP/Pb Se三维自组装超晶格/PVP/Al的电流-电压特性呈现出非常明显的电双稳特性和非易失记忆行为,在相同的电压下同时具有两种不同的导电状态:低电导的关态和高电导的开态。当PVP与Pb Se超晶格的质量比为1∶1时,器件性能最好,其最大电流开关比为7×104,经过104s仍几乎无衰减。通过对电流-电压曲线拟合,利用不同的导电模型对器件的载流子传输机制进行了解释。结果表明,Pb Se三维自组装超晶格作为电荷陷阱,可以俘获、储存及释放电荷,对器件的电双稳性能能起决定性作用。     

PEG掺杂对钙钛矿太阳能电池的影响

为了提高钙钛矿太阳能电池的能量转化效率,减小回滞现象,研究了聚乙二醇(PEG)掺杂钙钛矿太阳能电池阳极修饰层PEDOT∶PSS对器件性能的影响。通过电容-电压(C-V)测试分析了PEDOT∶PSS修饰层和钙钛矿层之间的界面电荷积累情况,通过电流密度-时间(J-T)瞬态光电流的测量研究了修饰层和钙钛矿层之间缺陷态情况。结果表明,PEG掺杂阳极修饰层提高了器件的短路电流(J_(sc))、开路电压(V_(oc))和填充因子(FF),光电转化效率从7.5%提高到10.0%,光电转化效率提高了33%,经过掺杂后的器件回滞现象明显减弱。这种通过PEG掺杂PEDOT∶PSS的方法能够减少器件界面处的电荷积累和缺陷态,从而减小器件的回滞现象,提高器件的能量转化效率。     

基于量子点和MEH-PPV的白光发光二极管的研究

利用无机纳米材料与有机聚合物材料相结合的方法制备白光发光二极管器件, 研究了蓝光量子点QDs(B)掺杂聚[2-甲氧基-5-(2-乙基己氧基-1, 4-苯撑乙烯撑](MEH-PPV) 复合体系的发光特性及量子点QDs(B) 掺杂浓度(质量分数)不同对器件发光特性的影响. 制备了ITO/PEDOT:PSS/MEH-PPV:QDs(B)/LiF/Al 结构的电致发光器件, 测试了器件的电致发光光谱和电学、光学特性. 当QDs掺杂浓度为40%, 驱动电压为8 V时器件能得到较为理想的白光发射. 同时, 对比研究了非掺杂体系的发光特性, 制备了结构为ITO/PEDOT:PSS/MEH-PPV/QDs(B)/LiF/Al的器件, 掺杂体系相较于非掺杂体系, 器件的最大亮度增大, 启亮电压降低, 并分析了掺杂体系器件性能改善的原因.     

串口型铁电存储器总剂量辐射损伤效应和退火特性

对一款商用串口I2C型铁电存储器进行了⁶⁰Coγ 辐射和退火实验, 研究了铁电存储器的总剂量效应和退火特性. 使用了超大规模集成电路测试系统测试了铁电存储器的DC, AC, 功能参数, 分析了辐射敏感参数在辐射和退火过程中的变化规律. 实验结果表明: 总剂量辐射在器件内产生大量氧化物陷阱电荷, 造成了铁电存储器外围控制电路MOS管阈值向负向漂移, 氧化物陷阱电荷引入附加电场使铁电薄膜受肖特基发射或空间电荷限制电流的作用, 产生辐射感生漏电流. 由于浅能级亚稳态的氧化物陷阱电荷数量上多于深能级氧化物陷阱电荷, 使得器件功能和辐射敏感参数在常温退火过程中快速恢复. 关键词： 铁电存储器 总剂量辐射 退火特性     

基于ITO/聚甲基丙烯酸甲酯/Al的有机阻变存储器SPICE仿真

探索了ITO/PMMA/Al器件的阻变机理及其SPICE电路仿真, 通过优化聚甲基丙烯酸甲酯(PMMA)层退火温度, 器件可实现连续擦-读-写-读操作. 基于不同退火温度PMMA薄膜的表面形貌研究, 构建了单层有机阻变器件的非线性电荷漂移模型, 以及描述该模型掺杂区界面移动的状态方程, 并通过反馈控制积分器建立了SPICE仿真电路. 最后, 代入器件实际测量参数, 得到与器件实际结果基本一致的电流-电压模拟曲线. 结果验证了单层有机器件的阻变机理, 说明该非线性电荷漂移模型的SPICE仿真在有机阻变器件仿真中同样适用. 关键词： 有机阻变存储器 非线性电荷漂移 SPICE仿真     

点接触金属/Pr0.7Ca0.3MnO3/Pt结构稳定的低电流电阻开关特性

利用自主开发的导电原子力显微镜控制Pt,W探针构成点接触金属/Pr0.7Ca0.3MnO3(PCMO)/Pt三明治结构,对其电流-电压(I-V)及脉冲诱导电阻开关(EPIR)特性进行了研究.研究发现,在10 nA限流下两种电极对应结构的I-V都表现出相当稳定的双极性电阻开关特性,以及大于100的电阻开关比.进一步测试发现,点接触W/PCMO/Pt器件具有在10 nA限流下稳定的EPIR特性以及100 pA限流下重复的双极性电阻开关特性.此电流比已报道的电流低3个数量级,表明此结构在低功耗存储器件方面的潜在应用.通过对比样品不同位置、不同限流、不同接触面积点接触Pt/PCMO/Pt的I-V回滞特性,把点接触器件在低电流下稳定、显著的电阻开关效应归结于小的器件面积导致强的局域电场加强了O离子迁移效应.     

不同应力下碳化硅场效应晶体管器件总剂量效应及退火特性

以碳化硅场效应晶体管器件作为研究对象,对其开展了不同电压、不同温度下的钴源辐照实验以及辐照后的退火实验.使用半导体参数分析仪测试了器件的直流参数,研究了器件辐照敏感参数在辐照和退火过程中的变化规律,分析了电压、温度对器件辐照退化产生影响的原因,也探索了退火恢复的机理.结果表明:辐照感生的氧化物陷阱电荷是造成碳化硅场效应晶体管器件电学参数退化的主要原因,电压和温度条件会影响氧化物陷阱电荷的最终产额,从而导致器件在不同电压、不同温度下辐照后的退化程度存在差异;退火过程中由于氧化物陷阱电荷发生了隧穿退火,导致器件电学性能得到了部分恢复.     

Electrical bistable devices using composites of zinc sulfide nanoparticles and poly-(N-vinylcarbazole)

N-dodecanethiol capped zinc sulfide(Zn S) nanocrystals were synthesized by the one-pot approach and blended with poly(N-vinylcarbazole)(PVK) to fabricate electrical bistable devices. The corresponding devices did exhibit electrical bistability and negative differential resistance(NDR) effects. A large ON/OFF current ratio of 104 at negative voltages was obtained by applying different amplitudes of sweeping voltage. The observed conductance switching and the negative differential resistance are attributed to the electric-field-induced charge transfer between the nanocrystals and the polymer,and the charge trapping/detrapping in the nanocrystals.     

Electrical bistability of tris-(8-hydroxyquinoline) aluminum (Alq3)/ZnSe organic-inorganic bistable device

We present that the electrical bistability in organic-inorganic bistable devices based on tris-(8-hydroxyquinoline) aluminum (Alq₃) and zinc selenide (ZnSe) with the tri-layer structure of Alq₃/aluminum (Al)/ZnSe. The current-voltage characteristics of the bistable device exhibit two electrical states as low (OFF state) and high (ON state) conductivity with ON/OFF ratio about four orders of magnitude. The conduction mechanisms in both ON and OFF states were analyzed by theoretical model. In the OFF state, the conduction mechanisms can be explained by thermionic emission model, which the ON state can be described by ohmic conduction model. The retention times of both states are more than 8000 s, and the device can reproduce continuous write-read-erase-read switching cycles. Moreover, for the organic-inorganic bistable device was kept at one year in ambient condition without encapsulation. The device still exhibited the electrical bistable behavior. Consequently, the ZnSe layer may be led to improve the lifetime property of the bistable device which acted as a self-encapsulating layer.     

Electrical bistability and charge-transport mechanisms in cuprous sulfide nanosphere-poly(<Emphasis Type="Italic">N</Emphasis>-vinylcarbazole) composite films

In this study, electrically bistable devices were fabricated by incorporating cuprous sulfide (Cu₂S) nanospheres with mean size less than 10 nm into a poly(N-vinylcarbazole) (PVK) matrix. A remarkable electrical bistability was clearly observed in the current–voltage curves of the devices due to an electric-field-induced charge transfer between the dodecanethiol-capped Cu₂S nanospheres and PVK. The maximum ON/OFF current ratio reached up to value as large as 10⁴, which was dependent on the mass ratios of Cu₂S nanospheres to PVK, the amplitude of the scanning voltages, and the film thickness. The charge-transport mechanisms of the electrically bistable devices were described on the basis of the experimental results using different theoretical models of organic electronics.     

PbS纳米晶修饰的ZnO/PVP复合电双稳器件阻变机制

采用简单旋涂工艺制备了具有ITO/PVP/ZnO NCs/PbS NCs/PVP/Al 夹心结构的有机/无机复合电双稳存储器件,与没有PbS纳米晶修饰层的器件ITO/PVP/ZnO NCs/PVP/Al相比,PbS纳米晶的引入使目标器件的开关比提高了2个数量级。结合器件的I-V曲线和能级结构分析了PbS 纳米晶修饰层对器件阻变和载流子传输的影响。结果显示,PbS纳米晶层的加入不仅优化了器件能级结构,有利于载流子的俘获和释放,还修饰了ZnO纳米晶的表面缺陷,降低了器件载流子的复合损耗。     

Electrical properties and switching mechanisms of flexible organic-inorganic bistable devices

The electrical properties of flexible organic-inorganic bistable devices fabricated with aluminum (Al) sandwiched between tris-(8-hydroxyquinoline) aluminum (Alq₃) and zinc selenide (ZnSe) layers were investigated. Current–voltage (I–V) measurements were conducted under conditions before, during, and after bending while changing the bending distance of the base plastic polyethylene terephthalate (PET) systematically. The maximum ON/OFF current ratios of the flexible bistable devices at flat and bent conditions were approximately 2.7×10⁴ and 1.9×10⁴, respectively. The conduction mechanisms in both ON and OFF states were analyzed by a theoretical model.     

Electrical and optical characteristics of various PPV derivatives (MEH-PPV, CzEH-PPV, OxdEH-PPV)

To investigate the electrical characteristics of polymer based light emitting diode (LED) devices, we fabricated the hole transport device (HTD) and the electron transport device (ETD). The ITO and Au with high work function were used as electrodes for the HTD, and the Al and Li:Al with low work function were used for the ETD. The active layer materials were poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV), poly[2-(N-carbazolyl)-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (CzEH-PPV), and poly[2-(4-tert-butylphenyl)-5-phenyl-1,3,4-oxadiazole-5(2-ethylhexoxy)-1,4-phenylene vinylene] (OxdEH-PPV). We measured the current density–applied field (J–E) characteristics of the HTD and ETD with various thickness at different temperatures. The results of the J–E curves were analyzed by using tunneling model, space charge limited conduction (SCLC) model, etc. In the SCLC model, the mobility of the hole and the electron of MEH-PPV is 10⁻⁶ and 10⁻⁸ cm²/Vs, respectively. For CzEH-PPV and OxdEH-PPV, the hole mobility is similar to the value of the electron mobility with 10⁻¹⁰ cm²/Vs. The luminescent efficiency of CzEH-PPV or OxdEH-PPV is higher than that of MEH-PPV. The results of photoconductivity of the systems qualitatively agrees with the result of the electrical measurement. We analyze that the balance of the electron and the hole mobility plays an important role for the efficiency of the LEDs.     

MEH-PPV/CdSe纳米复合器件的光电导特性的研究

以CdO和Se粉作为前驱物,在TOPO/TOP有机体系中制备了CdSe纳米晶,将其与聚合物MEH-PPV复合制备了复合光电导器件,研究了它的光电导特性,并将其与单层MEH-PPV光电导器件的特性进行了比较。结果发现纳米复合光电导器件的光电流响应光谱的2个峰的位置基本上与MEH-PPV和CdSe纳米晶的吸收峰的位置相对应,这说明CdSe纳米晶和聚合物MEH-PPV的吸收对光电流都有贡献,主要是由于CdSe纳米晶和MEH-PPV界面处的激子离化和电荷转移造成的。而且复合器件的光电流较单层有所增强,且MEH-PPV器件光谱的响应范围更宽。     

含新型噁二唑类电子传输层的有机发光二极管性能研究

含吡啶基的噁二唑类材料(PDPyDP)作为一种新型的电子传输层被有效地应用于可溶性聚对苯乙炔(MEHPPV)为发光层的双层结构的有机发光二极管器件中,并将其光电性能与MEHPPV的单层结构器件及分别含苯环(PDPDP)和反1,2亚乙烯基(PDVDP)的另外两种二唑类电子传输层的双层结构器件进行比较.EL光谱测量表明,它们的发光均来自于MEHPPV层,而它们相似的器件电流和光输出随驱动电场变化的规律表明这些器件中相似的电荷转移过程,但电致发光阈值电场对于双层结构器件来说低于单层结构器件,而插入PDPyDP层的器件,其阈值电场最低.在电流密度为50mA/cm²时,单层器件及各插入PDVDP、PDPDP和PDPyDP的双层器件的外量子效率相对值分别为3×10^-3%,5×10^-3%,2×10^-2%和0.1%.并分析了插入PDPyDP使器件发光性能提高最为明显的原因.通过将此类器件的结构等作进一步优化,其最佳量子效率可高达1.44%.