Performance improvement of MEH-PPV:PCBM solar cells using bathocuproine and bathophenanthroline as the buffer layers

In this work, bathocuproine (BCP) and bathophenanthroline (Bphen), commonly used in small-molecule organic solar cells (OSCs), are adopted as the buffer layers to improve the performance of the polymer solar cells (PSCs) based on poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV): [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction. By inserting BCP or Bphen between the active layer and the top cathode, all the performance parameters are dramatically improved. The power conversion efficiency is increased by about 70% and 120% with 5-nm BCP and 12-nm Bphen layers, respectively, when compared with that of the devices without any buffer layer. The performance enhancement is attributed to BCP or Bphen (i) increasing the optical field, and hence the absorption in the active layer, (ii) effectively blocking the excitons generated in MEH-PPV from quenching at organic/aluminum (Al) interface due to the large band-gap of BCP or Bphen, which results in a significant reduction in series resistance (Rs), and (iii) preventing damage to the active layer during the metal deposition. Compared with the traditional device using LiF as the buffer layer, the BCP-based devices show a comparable efficiency, while the Bphen-based devices show a much larger efficiency. This is due to the higher electron mobility in Bphen than that in BCP, which facilitates the electron transport and extraction through the buffer layer to the cathode.     

水溶性CuPc旋涂转速及退火方式对蓝色有机电致发光器件性能的影响

本文以Be(PP)₂为发光层、水溶性酞菁铜(WS-CuPc)为空穴注入层、NPB为空穴传输层,制备了结构为ITO/WS-CuPc/NPB/Be(PP)₂/LiF/Al的蓝色有机发光二极管(OLEDs).研究了WS-CuPc不同旋涂转速对器件性能的影响.并在WS-CuPc最佳旋涂转速的基础上,进一步研究了WS-CuPc薄膜不同退火方式对器件性能的影响.实验中,对WS-CuPc层采用了一种新的退火方式,即对ITO玻璃衬底先加热后旋涂WS-CuPc层,并与传统退火方式 关键词： 水溶性CuPc 蓝色有机电致发光 旋涂转速 退火方式     

具有{110}面的锐钛矿TiO_2单晶的可控合成与光催化性能

采用水热法合成了同时具有最高表面能{110}和{001}晶面的锐钛矿TiO2单晶,通过X射线衍射、扫描电镜和激光拉曼光谱等手段对样品的形貌和结构进行了表征,并系统考察了过氧化氢、氢氟酸和反应温度等关键因素对所得样品中{110}面比例的影响,实现了持续提高{110}面比例的过程.在光催化降解亚甲基蓝反应中,具有{110}面的锐钛矿TiO2单晶的光催化活性显著高于无{110}面的单晶.     

Application of TiO2 with different structures in solar cells

The application of TiO2-based devices is mainly dependent on their crystalline structure,morphology,size,and exposed facets.Two kinds of TiO2 with different structures,namely TiO2 pompons and TiO2 nanotubes,have been prepared by the hydrothermal method.TiO2 with different structures is characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),and Brunauer-Emmett-Teller(BET) surface area analysis.Solar cells based on poly(3-hexylthiophene)(P3HT) and TiO2 with different structures are fabricated.In the device ITO/TiO2/P3HT/Au,the P3HT is designed to act as the electron donor,and TiO2 pompons and TiO2 nanotubes act as the electron acceptor.The effects of the TiO2 structure on the performance of hybrid heterojunction solar cells are investigated.The device with TiO2 pompons has an open circuit voltage(Voc) of 0.51 V,a short circuit current(Jsc) of 0.21 mA/cm2,and a fill factor(FF) of 28.3%.Another device with TiO2 nanotubes has a V oc of 0.5 V,J sc of 0.27mA/cm2,and FF of 28.4%.The results indicate that the TiO2 nanotubes with a unidimensional structure have better carrier transport and light absorption properties than TiO 2 pompons.Consequently,the solar cell based on TiO2 nanotubes has a better performance.     

Influence of small-molecule material on performance of polymer solar cells based on MEH-PPV:PCBM blend

In this work,the influence of a small-molecule material,tris(8-hydroxyquinoline) aluminum (Alq 3),on bulk het-erojunction (BHJ) polymer solar cells (PSCs) is investigated in devices based on the blend of poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) and [6,6]-phenyl-C 61-butyric acid methyl ester (PCBM).By dop-ing Alq 3 into MEH-PPV:PCBM solution,the number of MEH-PPV excitons can be effectively increased due to the energy transfer from Alq 3 to MEH-PPV,which probably induces the increase of photocurrent generated by excitons dissociation.However,the low carrier mobility of Alq 3 is detrimental to the efficient charge transport,thereby blocking the charge collection by the respective electrodes.The balance between photon absorption and charge transport in the active layer plays a key role in the performance of PSCs.For the case of 5 wt.% Alq 3 doping,the device performance is deteriorated rather than improved as compared with that of the undoped device.On the other hand,we adopt Alq 3 as a buffer layer instead of commonly used LiF.All the photovoltaic parameters are improved,yielding an 80% increase in power conversion efficiency (PCE) at the optimum thickness (1 nm) as compared with that of the device without any buffer layer.Even for the 5 wt.% Alq 3 doped device,the PCE has a slight enhancement compared with that of the standard device after modification with 1 nm (or 2 nm) thermally evaporated Alq 3.The performance deterioration of Alq 3-doped devices can be explained by the low solubility of Alq 3,which probably deteriorates the bicontinuous D-A network morphology;while the performance improvement of the devices with Alq 3 as a buffer layer is attributed to the increased light harvesting,as well as blocking the hole leakage from MEH-PPV to the aluminum (Al) electrode due to the lower highest occupied molecular orbital (HOMO) level of Alq 3 compared with that of MEH-PPV.     

水溶性酞菁化合物对有机电致发光器件亮度和效率的影响

以水溶性酞菁铜(CuTcPc)为空穴注入层制备多层有机电致发光器件.ITO表面经过CuTcPc溶液修饰,能够提高空穴的注入能力,增加器件的电流密度和亮度.在有机电致发光器件中,空穴传输材料的空穴迁移率一般大于电子传输材料的电子迁移率,空穴是多数载流子;但是,CuTcPc修饰处理不仅提高了器件的电流密度和亮度,也提高了器...     

有机太阳能电池材料研究新进展

介绍了有机太阳能电池研究的背景、基本原理、分类,并对有机太阳能电池材料进行了全面综述,包括小分子太阳能电池材料、大分子太阳能电池材料、D-A体系材料和有机无机杂化体系材料.     

Performance improvement cells using bathocuproine of MEH-PPV：PCBM solar and bathophenanthroline as the buffer layers

In this work, bathocuproine （BCP） and bathophenanthroline （Bphen）, commonly used in small-molecule organic solar cells （OSCs）, are adopted as the buffer layers to improve the performance of the polymer solar cells （PSCs） based on poly（2-methoxy-5-（2-ethylhexyloxy）-1,4-phenylenevinylene） （MEH-PPV）： [6,6]-phenyl-C61-butyric acid methyl ester （PCBM） bulk heterojunction. By inserting BCP or Bphen between the active layer and the top cathode, all the performance parameters are dramatically improved. The power conversion efficiency is increased by about 70% and 120% with 5-am BCP and 12-nm Bphen layers, respectively, when compared with that of the devices without any buffer layer. The performance enhancement is attributed to BCP or Bphen （i） increasing the optical field, and hence the absorption in the active layer, （ii） effectively blocking the excitons generated in MEH-PPV from quenching at organic/aluminum （Al） interface due to the large band-gap of BCP or Bphen, which results in a significant reduction in series resistance （Rs）, and （iii） preventing damage to the active layer during the metal deposition. Compared with the traditional device using LiF as the buffer layer, the BCP-based devices show a comparable efficiency, while the Bphen-based devices show a much larger efficiency. This is due to the higher electron mobility in Bphen than that in BCP, which facilitates the electron transport and extraction through the buffer layer to the cathode.     

Solar cells based on the poly(N-vinylcarbazole):porphyrin: tris(8-hydroxyquinolinato) aluminium blend system

Organic solar cells based on poly(N-vinylcarbazole)(PVK):porphyrin:tris(8-hydroxyquinolinato) aluminium(Alq3) blend p-n junction systems have been fabricated in this work.The roles of the different components in the blend system and of the amount of porphyrin have been investigated.The 5,10,15,20-tetraphenylporphyrin(TPP) and 5,10,15,20-tetra(o-chloro)phenylporphyrinato-copper(CuTClPP) are used in the solar cells.The results show that TPP is better than CuTClPP in enhancing the performance of PVK:Alq3 solar cells.When the weight ratio of PVK:TPP:Alq3 is 1:1.5:1,the best performance of solar cell is obtained.The open circuit voltage(V oc) is 0.87 V,and the short circuit current(J sc) is 17.5 μA·cm 2.In the ternary bulk hereojunction system,the device may be regarded as a cascade of three devices of PVK:TPP,TPP:Alq3 and PVK:Alq3.PVK,TPP and Alq3 can improve the hole mobility,light absorption intensity and electron mobility of the ternary bulk hereojunction system,respectively.     

碳纳米管与生物分子的相互作用*

碳纳米管是一种具有特殊结构和性质的新型一维纳米材料,在生物学和临床医学上已有许多应用研究。大量研究表明,碳纳米管在药物载体、医学成像、疾病检测等方面有广泛的应用前景,碳纳米管与生物分子相互作用的具体机理和形式也成为目前研究的热门方向。本文总结了近几年来碳纳米管与氨基酸、多肽、蛋白质、酶、DNA等多种生物分子之间的相互作用,并对碳纳米管的生物学效应进行了相关综述。