Photoinduced degradation of organic solar cells with different microstructures

An in situ measurement setup is established to investigate the photoinduced degradation effects in a controllable inert gas ambient environment for the two different microstructures of poly(3-hexylthiophene)(P3HT) and [6,6]-phenyl-C61-butyricacid methyl ester(PCBM) bulk-heterojunction organic solar cells. The two devices are fabricated with the solvent vapor drying process followed by a thermal annealing(vapor drying device) and only a normal thermal annealing process(control device), respectively. Their power conversion efficiencies(PCEs) and aging features are compared. Their different degradation behaviors in light absorption are confirmed. In addition, irradiation-induced changes in both nanostructure and surface morphology of the P3HT:PCBM blend films treated with two different fabrication processes are observed through scanning electron microscopy and atomic force microscopy. Aggregated bulbs are observed at the surfaces for control devices after light irradiation for 50 h, while the vapor drying devices exhibit smooth film surfaces, and the corresponding device features are not easy to degrade under the aging measurement. Thus the devices having solvent vapor drying and thermal annealing show better device stabilities than those having only the thermal annealing process.     

P3HT:PCBM薄膜成膜过程对聚合物太阳能电池性能的影响

P3HT:PCBM薄膜的快速和缓慢成膜过程能显著的改变异质结聚合物太阳能电池性能.通过调节旋转时间以及薄膜退火前的间隔时间,研究了P3HT:PCBM混合薄膜缓慢生长所需最佳时间.结果表明,在转速800 r·min-1下旋涂薄膜,经过50～80 s的旋涂,接着放置样品薄膜30 min以上,然后再对薄膜进行退火处理,电池效...     

Programming resistive switching memory by a charged capacitor

The performances of bulk-heterojunction (BHJ) solar cells are investigated for time-dependent thermal annealing with different morphology evolution scales, having special consideration for the diffusion and aggregation of fullerene derivative molecules based on blends of poly(3-hexylthiophene):[6,6]-phenyl-C₆₁-butyric acid methyl ester (P3HT:PCBM). Meaningfully, rapid formation of dot-like and needle-like crystalline PCBM structures of a few micrometers up to 60 μm in size is obtained with thermal annealing treatment from 2 to 15 min, which dynamically reflects a fast process of PCBM molecule and cluster aggregation. Upon ultrasonic-assisted processing and annealing treatment, the scale of P3HT crystals is drastically increased in view of X-ray diffraction (XRD) patterns, leading to a high hole mobility. And, the P3HT domains can be gradually converted into larger P3HT crystals approved by the decreased full width at half-maximum in the XRD patterns. Corresponding current–voltage curves are measured in quantity and we propose a model to explain the effect of the crystalline degree of P3HT domains and aggregation of PCBM molecules and clusters on the phase segregation, expressing a viewpoint towards high performance of BHJ solar cells.     

基于透射率曲线确定聚合物太阳能电池功能层的光学常数和厚度

本文介绍了一种确定聚合物太阳能电池功能层光学常数和厚度的方法. 该方法借助于特定的色散模型拟合透射率测试曲线以获得功能层光学常数和厚度值. 文中比较了Forouhi-Bloomer和Lorentz-Oscillator模型在体异质结薄膜的透射率拟合计算中的适用性, 计算了poly(3-hexylthiophene)(P3HT)/[6,6]-phenylC₆₁-butyric acid methyl ester (PCBM)和 poly[2-methoxy-5-5(2'-ethyl-hexyloxy)-1,4-phenylenevinylene](MEH-PPV)/PCBM体异质结薄膜的光学常数和厚度. 拟合得到的曲线与实验曲线符合良好, 厚度计算的结果与台阶仪测量结果保持一致, 误差小于4%. 进一步分析得到的热退火和加入高沸点溶剂添加剂后P3HT/PCBM薄膜的光学常数和光学禁带值与相应器件伏安特性相符. 该方法适用于所有体异质结的功能层, 可用于聚合物太阳能电池的膜系优化和在线检测.     

Thermal Annealing Effects on the Absorption and Structural Properties of Regioregular Poly(3-Hexylthiophene) Films

Regioregular poly(3-hexylthiophene) (P3HT) was synthesized by a Grignard metathesis method. The annealed and fast cooled P3HT films were studied by UV-vis absorption spectroscopy, atomic force microscopy, and grazing incidence X-ray diffraction (GIXRD) measurements. It is demonstrated that thermal annealing at around the onset temperature of the melting point of the polymer results in the annealed film having the highest interchain and intrachain orders while preserving the original morphological features. However, the film that has the highest or lowest crystallinity does not have the strongest or weakest absorption. The lack of clear correlation between the absorption spectra and GIXRD data is explained by a quasi-ordered phase model, in which crystalline, amorphous, and quasi-ordered chains interconvert into each other depending on annealing temperature.     

退火处理ZnPc(OC_8H_(17)OPyCH_3I)_8阴极缓冲层的倒置有机太阳能电池

制备了以Zn Pc(OC8H17OPy CH3I)8为阴极缓冲层、P3HT∶PCBM为有源层的有机太阳能电池。对阴极缓冲层Zn Pc(OC8H17OPy CH3I)8薄膜分别进行了溶剂蒸汽退火和过渡舱惰性气体流退火处理,并利用原子力显微镜(AFM)对缓冲层表面形貌进行了表征。结果表明:这两种退火方法都使缓冲层形貌得以改善。电池效率从2.14%提高到3.76%,电流密度从8.12 m A/cm2提高到10.71 m A/cm2,填充因子从0.45提高到0.61。与传统器件相比,退火处理的阴极缓冲层器件的稳定性也得到了改善,器件寿命延长了1.4倍。这种简单阴极界面处理方法为改善聚合物太阳能电池性能提供了有效途径。     

不同环境压强下溶剂退火对聚合物太阳能电池性能的影响

通过改变溶剂退火时的环境压强控制溶剂的蒸发速率,在不同压强下进行加压溶剂退火制备了基于聚-3己基噻吩:富勒烯衍生物(P3HT:PCBM)的体异质结聚合物太阳能电池。X射线衍射(XRD)、紫外-可见吸收光谱(UV-Vis)以及原子力显微镜(AFM)的测试结果表明,增大溶剂退火的环境气压改善了薄膜的结晶度,增强了有源层的光吸收,提高了P3HT和PCBM的相分离程度,更有利于激子的解离和载流子传输。与在常压下溶剂退火相比,在2.0 MPa压强下对有源层进行溶剂退火的器件的光电转换效率提高了29%,达到了3.69%。     

Annealed Treatment Effect in Poly（3-hexylthiophene）：Methanofullerene Solar Cells

Polymer photovoltaic devices based on poly（3-hexylthiophene） （P3HT） ： [6,6]-phenyl-C61-butyricacid methyl ester （PCBM） 1：1 weight-ratio blend are reported. The effects of various annealing treatments on the device performance are investigated. Thermal annealing shows significant improvement of the device performances. For devices at 130℃ annealing, maximum power conversion efficiency （PCE） of 3.3% and All factor up to 60.3% is achieved under air mass 1.5, 100 m W/cm^2 illumination. We discuss the effect of thermal annealing by the results of ultraviolet-visible absorption spectroscopy （UV-vis）, dark current-voltage curve, atomic force microscopy （AFM）.     

Composition-dependent phase separation effects of organic solar cells using P3HT:PCBM as active layer and chromium oxide as hole transporting layer

Phase separation of the poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) active layer (ATL) was investigated by varying their relative ratio in the organic solar cells (OSCs). With the help of the UV/visible spectrophotometer, optical microscopy and scanning electron microscope, we found that the cluster of PCBM at the interface or surface was affected by Al cathode, the composition of the blends and thermal annealing. The disc-like shape crystals of PCBM substituted for the needle-like ones at higher PCBM compositions at the ATL/Al interface, which led to stronger contacts and bigger contact area. It could make short circuit current density increase, but may affect the blend morphology and result in parallel resistance and open circuit voltage decreased with the PCBM ratio increasing from 40 to 60%. The microstructure of the P3HT:PCBM ATL, determined by the composition dependent phase separation, supported the optimized performance of the OSCs with the composition of 40-50% PCBM.     

退火气压对于P3HT∶PCBM微观形貌及光伏性能的影响

通过精确设定不同的退火环境气压,实现对P3HT(Poly(3-hexylthiophene -2,5-diyl)与PCBM([6,6]-Phenyl C₆₁ butyric acid methyl ester)体系中聚噻吩结晶度以及共混相分离程度的控制,并在此基础上制备了结构为ITO/PEDOT∶PSS/P3HT∶PCBM/Al的正型光伏器件。在允许的压强设定范围内,器件各项性能参数均随退火环境压强的增大表现出先升高后下降的变化规律,并统一于气压设定为1 500 mTorr时获得最大值。从活性层的紫外-可见(UV-Vis)吸收光谱中发现P3HT在510 nm吸收峰以及550和600 nm肩峰附近的吸收强度随退火气压升高而增大,在气压为1 500 mTorr时达到最高,吸收强度的提升源于聚合物分子π—π堆叠的增加。原子力显微镜(AFM)进一步分析结果表明,高气压环境(>1 000 mTorr)能够促进P3HT∶PCBM共混组分在退火过程中形成较大程度的相分离,而当环境压强合适时(1 500 mTorr)适度的相分离利于聚合物形成良好有序结晶,从而能够提升活性层内部载流子传输能力,保证较高的短路电流与填充因子,制备的器件也因此表现出良好的光伏性能,光电转化效率达到3.56%。     

Nanoparticle agglomeration in polymer-based solar cells

We show that the morphology of polymer-based solar cells substantially changes after annealing using small angle neutron scattering. Phenyl-C61-butyric acid methyl ester (PCBM) is found reasonably well dispersed within the poly(3-hexylthiophene) (P3HT) rich phase after initial processing (spin coating). However, the PCBM structure coarsens after annealing, clearly evidenced by the increase in scattering intensity at a small wave vector. The change in morphology at the nanoscale is related to improved device performance and the simultaneous, contradictory, increase in photoluminescence.     

Effects of concentration and annealing on the performance of regioregular poly（3-hexylthiophene） field-effect transistors

This paper investigates the effects of concentration on the crystalline structure, the morphology, and the charge carrier mobility of regioregular poly(3-hexylthiophene) (RR-P3HT) field-effect transistors (FETs). The RR-P3HT FETs with RR-P3HT as an active layer with different concentrations of RR-P3HT solution from 0.5~wt% to 2~wt% are prepared. The results indicate that the performance of RR-P3HT FETs improves drastically with the increase of RR-P3HT weight percentages in chloroform solution due to the formation of more microcrystalline lamellae and bigger nanoscale islands. It finds that the field-effect mobility of RR-P3HT FET with 2~wt% can reach 5.78× 10^-3~cm²/Vs which is higher by a factor of 13 than that with 0.5~wt%. Further, an appropriate thermal annealing is adopted to improve the performance of RR-P3HT FETs. The field-effect mobility of RR-P3HT FETs increases drastically to 0.09~cm²/Vs by thermal annealing at 150~℃, and the value of on/off current ratio can reach 10^4.     

溶剂预处理结合热退火提升聚噻吩结晶度及其光伏性能

活性层的微观形貌在很大程度上决定了聚合物光伏器件的性能表现并依赖于制备工艺条件。为了改善薄膜内部分子排布结构并追求较高的器件光电转化效率,采用溶液法制备了基于P3HT：PCBM的聚合物太阳能电池（器件结构:ITO/PEDOT：PSS/P3HT：PCBM/Al）,通过改变器件制备流程中活性层退火处理工艺,研究了热退火、溶剂退火以及溶剂预处理结合热处理的双重退火对聚合物太阳电池性能的影响。研究发现:双重退火的光伏器件的各项性能参数均优于单一退火处理器件,获得了3.25%的光电转化效率。原子力显微镜及X射线衍射仪的表征结果进一步证明:双重退火处理能够在促进聚合物给体良好有序结晶的同时保证共混组分适度地相分离,从而有利于光生激子的解离以及载流子的传输。     

Effect of different annealing methods on ferroelectric properties of 0.95Pb(Sc0.5Ta0.5)O3-0.05PbTiO3 thin films

0.95Pb(Sc_0.5Ta_0.5)O₃-0.05PbTiO₃ thin films were prepared on LaNiO₃/SiO₂/Si substrate by radio frequency magnetron sputtering, and the films were annealed subsequently with repeated many times by two approaches: normal one-step rapid thermal annealing and innovative two-steps rapid thermal annealing. X-ray diffraction demonstrates that all the films were preferred (1 0 0) oriented and an appropriate repeat of annealing process can enhance perovskite phase of the films. Scanning electron microscopy suggests that the films treated by two-steps rapid thermal annealing show crack-free, uniform size grains and dense microstructure. Measurement of remnant polarization and leakage current dependence of electric field confirms that the films treated by two-steps rapid thermal annealing exhibit better ferroelectric properties than the films treated by one-steps rapid thermal annealing. The results reveal that microstructure plays an important role in enhanced ferroelectric properties of the 0.95Pb(Sc_0.5Ta_0.5)O₃-0.05PbTiO₃ thin films.     

掺杂石墨烯量子点对P3HT:PCBM太阳能电池性能的影响

为研究掺杂石墨烯量子点(GQDs)对聚合物电池的影响,采用溶剂热法制备了GQDs,掺杂到聚3-己基噻吩和富勒烯衍生物(P3HT∶PCBM)中作光敏层制备了聚合物太阳能电池。掺杂不同浓度的GQDs后,聚合物电池的开路电压和填充因子都比未掺杂器件高。GQDs掺杂质量分数为0.15%时,形成的掺杂薄膜平整、均匀,填充因子提高了17.42%。GQDs经还原后,随还原时间的延长,填充因子FF增大。到45 min时,电池的FF基本稳定,从31.57%提高至40.80%,提高了29.24%。退火后,获得了最佳的掺杂GQDs的聚合物太阳能电池,开路电压Voc为0.54 V,填充因子FF为55.56%,光电转换效率为0.75%。     

空间电荷限制电流法测量共混体系中空穴的迁移率

载流子迁移率测量是有机半导体材料与器件研究中的重要内容之一.以聚噻吩为电子给体材料, C₆₀的衍生物为电子受体材料,制备了一种单电荷传输器件.用空间电荷限制电流法测出了不同溶剂形成的 活性层及不同温度热处理后器件中空穴的迁移率.结果表明:器件中电荷的传输J-V曲线符合Mott-Gurney方程, 不同溶剂形成活性层中空穴具有不同的迁移率,高沸点的溶剂1, 2-二氯苯形成的活性层具有较高的空穴迁移率, 热处理有利于器件中空穴迁移率的提高.同时还进一步分析了空穴迁移率变化的原因.     

基于苯并二噻吩聚合物所制备的三元光电探测器的特性

本文采用P3HT:PTB7:PC61BM为活性层,制备了覆盖可见光范围的三元体异质结有机光电探测器(organic photodetectors,OPDs).利用原子力显微镜、紫外可见吸收光谱和荧光光谱等手段研究了PTB7添加到P3HT:PC61BM体系中对OPDs光学和电学性质的影响,发现当P3HT:PTB7:PC6...     

The improvement of bulk-heterojunction order in polymer photovoltaic device

The blend morphology and vertical arrangement are critical to the performance of organic bulk-heterojunction photovoltaic devices.In the present paper,the authors proposed a new annealing method that controls the blend morphology and vertical arrangement of two materials by means of simultaneously applying external electrical field and violet irradiation on the active layer of poly(3-hexylthiophene) (P3HT) and -phenyl C61-butyric acid methyl ester(PCBM) during annealing process.By using this annealing metho...     

Effect of Different Ionic Surfactants on the Structural,Photophysical, and Morphological Properties of Water-Based P3HT:PCBM Nanoparticle Dispersions and Films

Aqueous suspensions of composite nanoparticles of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C₆₁ butyric acid methyl ester (PCBM) are fabricated by miniemulsion method using three different ionic surfactants. The aim is to study how the length and conformation of the surfactants alkyl chains affect the properties of the nanoparticles. While the morphology and dimensions of the nanoparticles are similar, UV–vis spectroscopy evidences that the internal aggregation and ordering of the P3HT chains varies within the three nanoparticle formulations. The surfactant with branched alkyl chains promote the highest degree of ordering of P3HT chains in the nanoparticles (leading to increased conjugation length). In contrast, the lowest ordering is found for the nanoparticles with the surfactant having the shortest linear alkyl chain. The optical/structural properties of nanoparticles are partially retained in the films. Besides, the surfactant with branched alkyl chains favors the strongest coalescence of nanoparticles in the thin film, promoting a further ordering of the polymeric chains in the most external shell of the nanoparticles as evidenced by steady-state and time-resolved UV–vis spectroscopy and confocal fluorescence microscopy. These findings might guide the engineering of new surfactants for composite nanoparticles for optoelectronic applications.     

聚3-己基噻吩-b-聚十六烷氧基联烯嵌段聚合物的制备及其场效应性能

以溴代十六烷、丙炔醇为原料通过取代反应、还原重排反应制备了十六烷氧基联烯,然后以氯化(三环己基膦)镍作为催化剂,通过控制加料顺序一锅制备了聚3-己基噻吩-b-聚十六烷氧基联烯的嵌段聚合物。通过核磁共振氢谱和体积排除色谱对产物进行了表征和确证。对聚3-己基噻吩-b-聚十六烷氧基联烯嵌段聚合物的热学性能、光学性能及电学性能进行了研究。差示扫描量热法和热重分析结果表明,嵌段共聚物具有两个玻璃化转变温度及两个热分解温度,说明其具有明显相分离。以嵌段共聚物为半导体活性材料,制备了场效应晶体管器件。使用热退火对器件进行热处理,发现迁移率随退火温度的上升而提高。器件在200℃退火温度下的平均迁移率为7.03×10~(-4)cm~2·V~(-1)·s~(-1),最大迁移率为1.3×10~(-3)cm~2·V~(-1)·s~(-1),阈值电压为5.44 V。