三元P3HT:PTB7-Th:PCBM聚合物太阳能电池性能的研究

将窄带隙聚合物PTB7-Th作为第三种物质掺入到P3HT:PCBM中制备了双给体结构的三元聚合物太阳能电池, 并且通过改变PTB7-Th的浓度来研究PTB7-Th对器件性能的影响. 研究发现, 掺入PTB7-Th后, 聚合物太阳能电池的短路电流和填充因子同时获得了提高, 使器件的光电转换效率得到了改善. 进一步分析表明, PTB7-Th的加入能够拓宽活性层的吸收光谱, 增加活性层吸收的光子数目, 有利于短路电流的提升. PTB7-Th与P3HT之间以电荷转移的形式相互作用, 这种作用方式有利于激子的解离, 从而使器件的填充因子得到了提高.     

基于PTB7,Bis-PC_(70)BM,PC_(70)BM的高效率有机三元太阳能电池

我们将Bis-PC_(70)BM作为第二种电子受体混入基于PTB7:PC_(70)BM的聚合物太阳能电池中,制备了三元混合聚合物太阳能电池.相比于PC_(70)BM,Bis-PC_(70)BM的最低未占分子轨道(lowest unoccupied molecular orbital,LUMO)能级更高,所以掺入Bis-PC_(70)BM后器件的开路电压(V_(oc))得到了提升.Bis-PC_(70)BM在PTB7和PC_(70)BM之间起到桥梁的作用,因此在给体/受体界面创造了更多的电荷传递通道.而且从原子力显微镜中得到的结果来看,当混入质量比为3%的Bis-PC_(70)BM后薄膜的表面形貌更为平整,平均粗糙度从原来的1.87 nm降到了1.80 nm.能量转换效率(power conversion efficiency,PCE)达到7.00%,其中器件的V_(OC)为0.77 V,短路电流(J_(SC))为13.92 mA·cm~(-2),比PTB7:PC_(70)BM的器件效率6.07%提高了15%.     

TiO_2阴极缓冲层对Rubrene/C_(70)有机太阳能电池性能的改善

为了提高有机太阳能电池(OSCs)的性能,增强器件在空气中的稳定性,研究了TiO_2薄膜作为阴极缓冲层对OSCs器件性能的影响。制备了结构为ITO/TiO_2/C70/Rubrene/Mo O3/Al的OSCs器件。首先,通过测量器件效率,考察了TiO_2薄膜对Rubrene/C70电池的性能影响。接着,通过控制TiO_2薄膜厚度,研究了TiO_2厚度对器件性能的影响。实验结果显示,当TiO_2修饰层厚度比较薄时,器件的各性能参数较低,随着TiO_2厚度的不断增加,器件的各性能参数呈上升趋势;当TiO_2厚度为81 nm时,器件的各性能参数达到最佳,器件的功率转换效率为1.09%,电流密度为2.55 m A·cm-2,开路电压为0.88 V,填充因子为48.69%;当TiO_2厚度继续增加时,器件的各性能参数开始下降。对比没有TiO_2阴极修饰层的器件,最优时的Jsc、Voc、FF和PCE分别提高了37%、21%、17%和91%,并阐述了性能提高的原因。     

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∶PC61BM的质量比为8∶2∶10时,三元混合层的响应光谱扩展到780 nm,OPDs的响应度R在630,530,460 nm的光照和–1 V偏压下分别达到178,291,241 mA/W,比探测率D^*达到10¹² Jones,并与课题组之前成果P3HT∶PBDT-TT-C∶PC61BM为活性层的三元有机光电探测器做了对比.分析了两种基于苯并[1,2-b∶4,5-b]二噻吩(BDT)单元的聚合物PTB7与PBDT-TT-C分别添加到同一体系P3HT∶PC₆₁BM中产生的器件性能差距的现象,解释了PTB7由于氟原子的引入,对混合薄膜微观形貌的影响和对薄膜中光生载流子迁移率的提升的原因.这为制备性能更好的有机光电探测器提供了理论依据和方法.     

一种新的基于频域有限差分方法的小周期有机太阳能电池的光电特性

由MoO₃/Ag/MoO₃ （MAM）组成的多层膜结构非常有希望替代ITO作为有机太阳能电池中的透明阳极.然而,基于MAM结构的有机太阳能电池光吸收能力较弱.为此,引入了一种小周期短节距金属光栅,利用表面等离子激元增强活性层的光吸收.借助于频域有限差分方法求解麦克斯韦方程和半导体方程,探讨了有机太阳能电池结构的光学和电学性质.分析结果表明：与平面结构相比,活性层中的光吸收大大提高;同时,当凹槽宽度为4 nm,能量转换效率提高了49%.相关结果有助于更好地开发和利用无ITO层的有机太阳能电池.     

Analysis of hybrid donor layer in organic solar cells based on SubPc and rubrene

In this paper, photovoltaic characteristics of ITO/PEDOT:PSS/SubPc:Rubrene (mixed ratio R by weight)/C₆₀/Bphen/Ag organic solar cells (OSCs) are analyzed in detail. The intrinsic properties of a SubPc:rubrene doped layer on device performance were discussed based on theoretical analysis of the experimental OSCs. The ratio R was 0, 0.25, 0.5, and 0.75,1, respectively. The results showed that when R was 0.75 performing the best, which owned the highest short circuit current (J _sc ) 6.61 mA/cm² and highest power conversion efficiency (PCE) 2.44%, the FF was 41% and the open circuit current (V _oc ) was 0.905 V. The suitable HOMO level, absorption capacity, carrier transport ability and exciton diffusion length (L _D ) of organic material are very important for the performance of the device.     

二甲基亚砜添加剂对聚合物太阳能电池性能的影响

研究了二甲基亚砜(DMSO)掺杂浓度对基于聚(3-己基噻吩)(P3HT)和(6,6)-苯基碳60丁酸甲酯(PCBM)为有源层的聚合物太阳能电池性能影响。结果表明,掺杂DMSO可以提高聚合物太阳能电池短路电流密度和填充因子。DMSO掺杂质量比为3%时,电池短路电流密度提高到7.88 mA·cm-2,填充因子为55.5%。能量转换效率达到2.54％,相比没有掺杂DMSO的电池,能量转换效率提高了17%。傅里叶变换红外光谱被用于鉴定和分析掺杂DMSO对材料P3HT∶PCBM化学性质的影响。傅里叶变换红外光谱表明,掺杂后P3HT和PCBM的化学性质都没有改变。为分析掺杂DMSO改善器件能量转换效率的原因,通过紫外-可见光谱和电流密度-电压特性曲线分别表征器件的光吸收能力以及电致发光器件的载流子迁移率。与P3HT∶PCBM薄膜相比,P3HT∶PCBM∶DMSO薄膜在可见光范围内的吸收峰有明显红移且吸收强度增强。可见光吸收的改善是实现短路电流密度提高的有力保障。太阳能电池性能的增强是因为DMSO的掺杂提高了P3HT∶PCBM的载流子迁移率和吸收光谱宽度。     

基于金纳米棒@二氧化硅表面等离子体共振增强的有机太阳能电池

把包裹SiO₂的金纳米棒（Au NRs@SiO₂）掺杂到有机太阳能电池的活性层中,利用表面等离子体共振效应来增强活性层对光的吸收,从而提高有机太阳能电池的能量转换效率。研究了不同掺杂浓度和不同包裹厚度对电池性能的影响。结果表明,掺杂浓度为1.5%时,器件性能最佳,能量转换效率达到4.02%;SiO₂壳层厚度为3 nm时,转换效率达到4.38%,较标准电池提升了29.2%。     

PTCBI作为阴极修饰层对Rubrene/C70器件性能的影响

制备了结构为ITO/MoO₃(6 nm)/Rubrene (30 nm)/C₇₀ (30 nm)/PTCBI(x nm)/Al (150 nm)器件, 研究了四羧基苝的衍生物PTCBI作为阴极修饰层对Rubrene/C₇₀有机太阳能电池的作用. 实验结果显示, 在C₇₀与Al电极之间插入PTCBI 后, 电池性能得到明显改善; 分析表明, 插入PTCBI后, 活性层与阴极形成了良好的欧姆接触, 提高了器件的内建电场, 同时PTCBI避免了激子与Al电极的接触, 减少了在制备过程中高动能Al对C₇₀的破坏. 进一步考察了PTCBI厚度对电池的性能的影响, 结果显示, 厚度为6 nm的PTCBI 层器件性能最佳, 其开路电压(V_OC)、填充因子(FF)、短路电流密度(J_SC)与功率转换效率(ηP)与未插入PTCBI修饰层的器件相比分别提高了70.4%, 55.5%, 125.1%, 292.2%. 当PTCBI的厚度大于6 nm时, 激子解离后产生的自由电子会在PTCBI与阴极界面积累, 导致器件J-V曲线出现S形.     

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.     

The effect of annealing treatment on the performance of bulk heterojunction solar cells with donor and acceptor different weight ratios

Bulk heterojunction organic solar cells(OSCs) based on the blend of poly(2-methoxy-5(2'-ethyl-hexyloxy)-1,4-phenylenevinylene(MEH-PPV) and [6,6]-phenyl C61 butyric acid methyl ester(PCBM) with different weight ratios(from 1:3 to 1:5) have been fabricated and the effect of annealing treatment on the performance of OSCs has also been studied.Experimental results point to the best optimized doping concentration 1:4 for MEH-PPV:PCBM.Furthermore,it is found that the devices with annealing treatment at 150℃ with ...     

小分子叠层有机太阳能电池的界面层优化

为了提高双结叠层有机太阳能电池(OSCs)的性能,我们对有机小分子叠层OSCs的中间层(IL)、阴极界面层(CL)和活性层进行了优化。首先,研究不同低功函数的金属纳米粒子(Mg、Ag、Al和Ca)作为IL对叠层OSCs性能的影响,得到了最优的IL材料为0.1 nm厚的金属Al,使得叠层OSCs的PCE提升了50.9%。其次,研究了不同低功函数金属(Mg、Al和Ca)作为CL对叠层OSCs性能的影响,并得到了最优的CL金属材料为Mg,与Al作为CL的叠层OSCs对比,采用Mg作为CL的器件PCE提升了20.7%。最后采用窄带隙材料DTDCTB取代中带隙材料boron subphthalocyanine chloride(SubPc)作为后子电池的活性层,与仅采用SubPc的叠层OSCs相比,PCE提升了30.2%。当前后子电池均采用体异质结结构后,最终叠层OSCs的PCE达到了4.04%,与最初未优化前OSCs的PCE(2.1%)相比,最优OSCs的PCE提升了92.4%。     

基于卟啉化合物的异质结有机太阳能电池

采用混合溶剂制备了四苯基卟啉(TPP)及其铜配合物(TPPCu)和氯化对甲氧基四苯基铁卟啉(TMPPFeCl),将三种卟啉化合物和富勒烯的衍生物(PCBM)分别共混,制备异质结太阳能电池。器件结构是ITO/porphyrin∶PCBM/Al,研究此类电池的性能。结果显示基于TPP∶PCBM的器件性能最优,其短路电流密度(JSC)是0.98mA.cm-2,开路电压(VOC)是0.52V,填充因子(FF)为30.1%。TPP是三种卟啉化合物中最佳的给体材料。进而考察了TPP∶PCBM的不同浓度配比对器件性能的影响。TPP∶PCBM的最佳浓度配比为1∶1,增加或减少TPP的量都会使器件的短路电流和开路电压降低,对填充因子的影响不大。     

使用PTB7作为阳极修饰层提高有机发光二极管的性能

采用poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl][3-?uoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]](PTB7)作为有机发光二极管器件的阳极修饰层,制备了结构为indium tin oxide(ITO)/PTB7(不同浓度)/N,N’-Bis(naphthalen-1-yl)-N,N’-bis(phenyl)benzidine(NPB,40 nm)/8-hydroxyquinoline(Alq3,60 nm)/LiF(1 nm)/Al的系列器件,同时研究了不同浓度的PTB7对器件性能的影响.PTB7的最佳浓度为0.25 mg/mL,器件性能得到明显的改善,起亮电压为4.3 V.当驱动电压为14.6 V时,最大亮度为45800 cd/m2,最大电流效率为9.1 cd/A.与没有PTB7修饰的器件相比,其起亮电压降低了1.9 V,最高亮度提升了78.5%.器件性能提高归因于PTB7的插入使得空穴注入和传输能力大大改善.     

Automated measurement of fat infiltration in the hip abductors from Dixon magnetic resonance imaging

PurposeIntramuscular fat infiltration is a dynamic process, in response to exercise and muscle health, which can be quantified by estimating fat fraction (FF) from Dixon MRI. Healthy hip abductor muscles are a good indicator of a healthy hip and an active lifestyle as they have a fundamental role in walking. The automated measurement of the abductors' FF requires the challenging task of segmenting them. We aimed to design, develop and evaluate a multi-atlas based method for automated measurement of fat fraction in the main hip abductor muscles: gluteus maximus (GMAX), gluteus medius (GMED), gluteus minimus (GMIN) and tensor fasciae latae (TFL).MethodWe collected and manually segmented Dixon MR images of 10 healthy individuals and 7 patients who underwent MRI for hip problems. Twelve of them were selected to build an atlas library used to implement the automated multi-atlas segmentation method. We compared the FF in the hip abductor muscles for the automated and manual segmentations for both healthy and patients groups. Measures of average and spread were reported for FF for both methods. We used the root mean square error (RMSE) to quantify the method accuracy. A linear regression model was used to explain the relationship between FF for automated and manual segmentations.ResultsThe automated median (IQR) FF was 20.0(16.0–26.4) %, 14.3(10.9–16.5) %, 15.5(13.9–18.6) % and 16.2(13.5–25.6) % for GMAX, GMED, GMIN and TFL respectively, with a FF RMSE of 1.6%, 0.8%, 2.1%, 2.7%. A strong linear correlation (R² = 0.93, p < .001, m = 0.99) was found between the FF from automated and manual segmentations. The mean FF was higher in patients than in healthy subjects.ConclusionThe automated measurement of FF of hip abductor muscles from Dixon MRI had good agreement with FF measurements from manually segmented images. The method was accurate for both healthy and patients groups.     

Donor-acceptor conjugated copolymer with high thermoelectric performance: A case study of the oxidation process within chemical doping

The doping process and thermoelectric properties of donor-acceptor(D-A)type copolymers are investigated with the representative poly([2,6-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b]dithiophene]3-fluoro-2-[(2-ethylhexyl)-carbonyl]thieno[3,4-b]thiophenediyl))(PTB7-Th).The PTB7-Th is doped by Fe Cl;and only polarons are induced in its doped films.The results reveal that the electron-rich donor units within PTB7-Th lose electrons preferentially at the initial stage of the oxidation and then the acceptor units begin to be oxidized at a high doping concentration.The energy levels of polarons and the Fermi level of the doped PTB7-Th remain almost unchange with different doping levels.However,the morphology of the PTB7-Th films could be deteriorated as the doping levels are improved,which is one of the main reasons for the decrease of electrical conductivity at the later stage of doping.The best electrical conductivity and power factor are obtained to be 42.3 S·cm^-1;and 33.9μW·mK^-1,respectively,in the doped PTB7-Th film at room temperature.The power factor is further improved to 38.3μW·mK^-1;at 75℃.This work may provide meaningful experience for development of D-A type thermoelectric copolymers and may further improve the doping efficiency.     

利用吡啶添加剂提高钙钛矿太阳能电池的光伏性能

研究了吡啶作为添加剂对一步法制备甲胺铅碘钙钛矿太阳能电池光电性能的影响.利用SEM、AFM、XRD、UV-Vis、PL等手段研究了不同吡啶掺杂浓度对制备的CH3 NH3 PbI3薄膜的表面形貌、结晶度和光学性能的影响.研究结果表明:少量的吡啶掺杂可以提高钙钛矿薄膜的覆盖率及降低薄膜的表面粗糙度.当在CH3 NH3 PbI3前驱体溶液中添加体积分数为1%的吡啶时,制备的钙钛矿太阳能电池的能量转换效率达到7.33%,而未加吡啶的对比器件效率仅为1.01%.进一步添加吡啶会导致钙钛矿材料的降解.     

Enhanced Efficiency of Polymer： Fullerene Bulk Heterojunction Solar Cells with the Insertion of Thin TiO2 Layer near the LiF/A1 Electrode

The insertion layer of TiO2 between polymer-fullerene blend and LiF/AI electrode is used to enhance the shortcircuit current Isc and fill factor （FF）. The solar cell based on the blend of poly[2-methoxy-5-（2＇-ethylhexyloxy）- 1,4-phenylenevinylene] （MEH-PPV） and C60 with the modifying layer of TiO2 （about 20nm） shows the open- circuit Voc of about 0.62 V, short circuit current Isc of about 2.35 mA/cm^2, filling factor FF of about 0.284, and the power conversion efficiency （PCE） of about 2.4% under monochromatic light （50Onto） photoexcitation of about 17mW/cm^2. Compared to ceils without the TiO2 layer, the power conversion efficiency increases by about 17.5%. Similar effect is also obtained in cells with the undoped MEH-PPV structure of ITO/PEDOT：PASS/MEH- PPV/（TiO2）LiF/AI. The improved solar cell performance can be attributed to enhanced carrier extraction efficiency at the active layer/electrode interfaces when TiO2 is inserted.     

窄带有机光电探测器的优化设计

针对基于无机材料的光电探测器需要借助滤光器或棱镜耦合实现窄带响应,提出了一种通过有机材料制备窄带光电探测器并提高吸收峰值和降低半高全宽的方法和结构。该器件由分布布拉格反射器和有机光电二极管构成。有机光电二极管的顶电极和底电极之间构成光学微腔。采用传输矩阵法,详细分析了分布布拉格反射器的中心波长、有机光电二极管透明顶电极和光敏感层的厚度对有机光电探测器吸收性能的影响。研究结果表明,Tamm等离激元共振波长接近光敏感层的光学带隙时,可获得半高全宽小于20 nm的窄带响应,并且吸收峰值在70%以上。基于PTB7∶PC~(71)BM和PTB7-Th∶IEICO-4F的有机光电探测器分别可用于探测红光和近红外光。该研究从基本物理机制出发,结合材料和器件结构可将有机光电探测器的响应窗口从可见光拓展至近红外光。     

“薄膜即是界面，界面即是薄膜”：二维有机半导体晶体的研究进展

自首次于聚乙炔发现导电现象以来,具有共轭结构的有机半导体材料赖其种类丰富多样、 制备工艺简捷低耗、以及优异的机械柔性等特点,在“后硅时代”中有望以先进光电子设备展现 其广阔前景,因而多年来备受学界和产业界的瞩目。如何进一步阐明有机半导体中结构和性能之 间的关系,探索电荷载流子微观动力学行为,构筑高性能、新功能的有机光电子器件,是当下有 机电子学领域的前沿核心问题,也是保证其持续发展的基石。近年来,二维有机半导体晶体材料 在秉持高度有序的分子排列与极低的杂质缺陷浓度等优点的同时,更是以“薄膜即是界面、界面 即是薄膜”为一帜,克服传统体材料在研究与应用中的瓶颈,为揭示材料构性关系及其中基本物 理过程提供了良好的平台,也是实现多样化的新型有机光电子器件的理想材料,有望为微纳电子 领域带来新一轮变革。本文从二维有机半导体晶体的制备工艺、电荷载流子微观动力学行为,再 到新型器件的光电功能应用等方面,综述了最新研究进展,做出总结和展望,并提出目前面临的 挑战及未来研究方向,旨在为进一步深入理论研究,结合有机材料与先进技术,推动有机电子学 的发展提供有益帮助。