ZnO纳米颗粒表面缺陷对有机太阳能电池性能的影响

用温度控制ZnO纳米 颗粒粒径的大小,研究了颗粒粒径对表面缺陷的影响。由透射电镜(TEM)、紫外-吸收光谱 和荧光光谱测试表明,随着反应温度升高,ZnO纳米颗粒的尺寸增加,比表面积显著下降, 表面缺陷的体密度降低。将不同反应温 度下的ZnO纳米颗粒应用于ITO/ZnO/P3HT:PCBM/MoO₃/Ag结构的有机太阳能电池中,进一 步研究了缺陷对电池性能的影 响。实验结果表明,60℃下ZnO纳米颗粒薄膜作为电子传输层的器件 效果最好,电池效率可以达到3.05%。 这表明在一定范围内,ZnO纳米颗粒越大,缺陷密度越低,越有利于器件中电子的传输从而 提高太阳能电池器件的短路电流密度和光电转化效率。     

等离激元太阳能电池概述

贵金属纳米粒子的表面等离激元共振峰附近的光散射可以有效的增强薄膜太阳能电池光吸收效率.基于等离激元方法设计的太阳能电池可以很大程度上增强光吸收,并且减少太阳能电池的光吸收层厚度从而减小体积.本文针对等离激元增强太阳能电池性能的原理进行介绍,并且对其未来发展趋势进行了展望.     

等离激元共振增强多晶硅薄膜太阳电池性能研究

采用磁控溅射方法,在多晶硅薄膜太阳电池表面沉积了不同粒径大小的Au纳米粒子,利用粒径大小可调控的Au纳米粒子的局域表面等离激元共振增强效应(LSPR),对入射光中的可见光区域实现“光俘获”;采用UV-vis吸收光谱对LSPR进行了研究,结果表明,LSPR能够有效拓展Au纳米粒子的光谱响应范围(400～800 nm),并且,随着Au纳米粒子粒径的增大,LSPR共振吸收峰呈现出明显“红移”;同时,通过SERS表征,证实LSPR能够有效增强Au纳米粒子周围的局域电磁场强度;最后,多晶硅太阳电池的J-V特性曲线表明,当Au纳米粒子溅射时间为50 s时,多晶硅太阳电池光电转换效率(η)最高为14.8％,比未修饰Au纳米粒子的电池η提高了42.3％.     

超声退火形成片状PCBM堆积聚合物太阳电池研究

采用超声退火方法制备了P3HT/PCBM聚合物有机太阳电池。测试结果表明:超声退火40℃制备的电池能量转换效率最好,最优器件的能量转换效率达到了5.16%,这主要归因为超声退火40℃的电池薄膜内形成了片状PCBM堆积,有效地提高了器件的电子迁移率和太阳能吸收效率。     

有机层／阴极界面修饰对体异质结聚合物太阳能电池性能的影响

通过制备四种不同结构的器件,详细分析研究了活性层／阴极界面修饰对P3HT:PCBM聚合物体异质结太阳能电池性能的影响。当在P3HT:PCBM薄膜上旋涂一层PCBM,并蒸镀0.5 nm LiF时所制备的器件的填充因子和光电转换效率都得到较大的提高。对器件的光电性能和薄膜的形貌进行深入分析,阐明界面修饰的作用机理。     

表面等离子体激元增强薄膜太阳电池研究进展

表面等离子体激元共振是金属纳米结构非常独特的光学特性,对基于表面等离子体激元共振的纳米结构体系的研究已形成了一门新兴的学科,即表面等离子体光子学。可以利用金属纳米颗粒光散射、近场增强以及高度局域的表面等离子体极化激元增强薄膜太阳电池光吸收,提高电池转换效率。当前,表面等离子体光子学应用于太阳电池的设计已成为国际上光伏研究迅猛发展的一个热点。文章主要介绍表面等离子体激元增强薄膜太阳电池光吸收的原理及其在光伏器件中应用的最新研究进展。     

聚合物掺杂富勒烯衍生物光伏特性的研究

采用聚3-己基噻吩(P3HT)与富勒烯衍生物(PCBM)混合制备复合光伏器件,器件结构为ITO/PEDOT∶PSS/P3HT∶PCBM/Al。通过PCBM不同掺杂浓度的掺杂体系光伏特性的研究发现,P3HT∶PCBM质量比为1∶4时,器件显示出较好的光伏特性,开路电压为0.69 V,在光强为90 mW/cm2的白光(光源为氙灯)激发下,器件的短路电流密度为6.73 mA/cm2,填充因子为0.33,能量转换效率达到1.7%。     

超薄PCBM层提高有机太阳电池效率

为研究超薄PCBM层对有机太阳电池的影响,制备了含和不含超薄PCBM层的两种不同结构的体相异质结太阳电池,电池结构分别为:ITO/PEDOT:PSS/P3HT+PCBM/PCBM/AI,ITO/PEDOT:PSS/P3HT+PCBM/Al.测试结果表明:所制备电池的开路电压分别为0.599 2V和0.572 7 V,能量转换效率分别为2.24％、1.21％,超薄PCBM层起到了电子传输的作用.     

聚合物太阳能电池研究获新进展

聚合物太阳能电池一般由共轭聚合物给体和富勒烯衍生物受体的共混膜夹在ITO透明正极和金属负极之间所组成,具有结构和制备过程简单、成本低、重量轻、可制备成柔性器件等突出优点,近年来成为国内外研究热点。结构规整的聚（3-己基）噻吩（P3HT）和可溶性C60衍生物PCBM是最具代表性的给体和受体光伏材料。基于P3HT／PCBM的光伏器件能量转换效率稳定．达到3．5％～4．0％左右,使这一体系成为聚合物太阳能电池研究的标准体系。     

不同旋涂速率对聚合物太阳电池性能的影响

以聚3己基噻吩(P3HT)和[6,6]-phenyl-C61-butyric acid methyl ester(PCBM)为活性层材料制成聚合物太阳电池,通过控制活性层旋涂速率控制活性层厚度。从不同活性层厚度器件的吸收光谱、原子力及器件各项性能参数详细分析了不同活性层旋涂速率对太阳电池性能的影响。结果表明:旋涂速率为1 000 r/min时,电池具有最佳性能,光电转换效率最高为1.54%。     

Flexible solar cells based on PCBM/P3HT heterojunction

[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) / poly (3-hexylthiophene) (P3HT) heterojunction has not only the absorption in ultraviolet light for PCBM,but also the absorption in visible light for P3HT, which widens the incident light harvest range, improving the photoelectrical response of hybrid solar cell effectively.Using conducting polymers blend heterojunetion consisting of C60 derivatives PCBM and P3HT as charge carrier transferring medium to replace I3-/I- redox electrolyte and dye, a novel flexible solar cell was fabricated in this study.The influence of PCBM/P3HT mass ratio on the photovoltaic performance of the solar cell was also studied.flexible solar cell achieved a light-to-electric energy conversion efficiency of 1.04%, an open circuit voltage fill factor (FF) of 0.46.     

Morphology modulation of organic photovoltaics with block copolymer additive based on rational design strategies

Organic photovoltaics are a promising alternative to silicon-based solar cells with benefits of low-cost production and large scalability. However, its performance is restricted by a non-equilibrium phase-separated morphology. Additive compositions of block copolymer P3HT-b-PFTBT are most likely to mix up and form donor and acceptor morphologies. The parallel bulk-heterojunction model was proposed to show the characteristic photovoltaic parameters and the effect of the parallel cascading heterojunction formation made up of isolated PCBM acceptor domains. We demonstrate block copolymer-based stretchable solar cells on plastic foil substrates, with good power conversion efficiency. To compare the efficiency and stretchability, organic photovoltaic devices were constructed using P3HT/PC₆₁BM, PTB7/PC₇₁BM and P3HT/P3HT-b-PFTBT/PCBM active layer combinations. We find that through rational design of the component ratio, the block-copolymer-based solar cell can withstand tensile strain up to 37%.     

Organic solar cells using plasmonics of Ag nanoprisms

We demonstrate plasmonic effects in bulk heterojunction organic solar cells (OSCs) consisting of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) by incorporating silver (Ag) triangular shaped nanoparticles (nanoprisms; NPSs) into a poly(3,4-ethylenedioxythiophene) buffer layer. The optical absorption and geometric characteristics of the Ag NPSs were investigated in terms of their tunable in-plane dipole local surface plasmon resonance (LSPR) bands. The photovoltaic characteristics showed that the power conversion efficiency (PCE) of the plasmonic OSCs was enhanced by an increase of short circuit current (J_sc) compared to that of the reference cells without any variation in electrical properties. The enhanced J_sc is directly related to the enhancement of optical absorption efficiency by the LSPR of the Ag NPSs. We measured the photovoltaic characteristics of the plasmonic OSCs with various distances between the Ag NPSs and the P3HT:PCBM active layer, in which the PCEs of the plasmonic OSCs decreased with increasing distance. This suggests that the increase of photocurrent and optical absorption was due to near field enhancement (i.e., intensified incident light on the active layer) by the LSPR of the Ag NPSs.     

Conversion efficiency improvement mechanisms of polymer solar cells by balance electron–hole mobility using blended P3HT:PCBM:pentacene active layer

To improve the power conversion efficiency of polymer solar cells, the blended P3HT:PCBM:pentacene active layer was used to balance hole–electron mobility and roughen surface. Using space-charged-limited current model to analyze the hole-only devices and the electron-only devices, the P3HT:PCBM:pentacene (weight ratio = 1:0.8:0.09) active layer exhibited balance hole–electron mobility. Compared with the power conversion efficiency of 3.46% of the conventional polymer solar cells using P3HT:PCBM (1:0.8) active layer, the power conversion efficiency of 4.42% was obtained. In other words, the power conversion efficiency was improved about 27.5%.     

Laser-induced crystallization and conformation control of poly(3-hexylthiophene) for improving the performance of organic solar cells

Femto-second laser irradiation on P3HT:PCBM solutions have been demonstrated to have a significant impact on the conformational structures and photovoltaic performance of the resultant thin films. The crystallinity and edge-on/face-on conformations of P3HT and the aggregation of PCBM can be manipulated by controlling the wavelength (400–800 nm) and illumination duration (1–3 h) of the lasers. Grazing incidence wide- and small-angle X-ray scattering (GIWAXS and GISAXS) have been simultaneously utilized to characterize the nanostructures of the P3HT:PCBM blend films spin-cast from pristine and laser-irradiated solutions. The results show that the crystallinity, π-π* stacking and face-on conformations of P3HT can be enhanced as a result of the laser irradiation at 500 nm for 3 h. Furthermore, the diffusion and aggregation of PCBM molecules are suppressed by the photo-induced dimerization, as evidenced by the Raman spectra of the films cast from laser-irradiated PCBM solutions. The time-resolved fluorescence decay profiles show the charge transfer efficiency is improved, which may correlate to the supramolecular ordering of the polythiophene chains and the optimized phase separation in P3HT:PCBM composite. In the P3HT:PCBM active layer of the organic solar cells, more efficient charge transport and fine interpenetrating networks can be achieved due to the improved conformational microstructures. Consequently, the short-circuit current densities and power conversion efficiencies can be enhanced in organic solar cells based on the laser-irradiation processed P3HT:PCBM solutions.     

Cooperative plasmon enhanced organic solar cells with thermal coevaporated Au and Ag nanoparticles

Cooperative plasmon enhanced small molecule organic solar cells are demonstrated based on thermal coevaporated Au and Ag nanoparticles (NPs). The optimized device with an appropriate molar ratio of Au:Ag NPs shows a power conversion efficiency of 3.32%, which is 22.5% higher than that of the reference device without any NPs. The improvement is mainly contributed to the increased short-circuit current which resulted from the enhanced light harvesting due to localized surface plasmon resonance of Au:Ag NPs and the increased conductivity of the device. Besides, factors that determining the performance of the Au:Ag NPs cooperative plasmon enhance organic solar cells are investigated, and it finds that the thickness of MoO₃ buffer layer plays a crucial role. Owing to the different diameter of the thermal evaporated Au and Ag NPs, a suitable MoO₃ buffer layer is required to afford a large electromagnetic enhancement and to avoid significant exciton quenching by the NPs.     

The dual localized surface plasmonic effects of gold nanodots and gold nanoparticles enhance the performance of bulk heterojunction polymer solar cells

In this study, we investigated the effects of plasmonic resonances induced by gold nanodots (Au NDs), thermally deposited on the active layer, and octahedral gold nanoparticles (Au NPs), incorporated within the hole transport layer, on the performance of bulk heterojunction polymer solar cells (PSCs) based on poly(3-hexyl thiophene) (P3HT) and [6,6]-phenyl-C₆₁butyric acid methyl ester (PC₆₁BM). Thermal deposition of 5.3-nm Au NDs between the active layer and the cathode in a P3HT:PC₆₁BM device resulted in the power conversion efficiency (PCE) of 4.6%—that is 15% greater than that (4.0%) for the P3HT:PC₆₁BM device without Au NDs. The Au NDs provided near-field enhancement through excitation of the localized surface plasmon resonance (LSPR), thereby enhancing the degree of light absorption.     

High efficiency polymer solar cells with wet deposited plasmonic gold nanodots

We report the enhanced performance of poly(3-hexylthiophene)/[6,6]-phenyl-C₆₁ butyric acid methyl ester (P3HT/PCBM) bulk heterojunction solar cells with wet deposited interfacial gold nanostructures on their indium tin oxide (ITO) surfaces. To produce localized surface plasmons at the ITO surfaces, gold nanostructures were fabricated through the layer-by-layer deposition of gold nanorods onto the ITO substrates and transformed into nanodots through a thermally induced shape transition. The incorporation of plasmonic gold nanodots on the ITO surface was found to result in an increase in the power conversion efficiency from 3.04% to 3.65%, which is due to the presence of the resulting plasmon field.     

Small organic additive to improve the charge separation in an inverted bulk heterojunction organic photovoltaic

A small organic molecule of 2,3-bis(5-bromothiophene-2-yl)acrylonitrile (DTDBAL) was synthesized for the first time and introduced into an active layer consisting of poly-3-hexylthiophene (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), in order to improve the performance of an inverted bulk heterojunction organic photovoltaic. The short-circuit current of the device was improved owing to the formation of a cascade band alignment of P3HT/DTDBAL/PCBM which enhanced the exciton dissociation and charge transport. Meanwhile, the open-circuit voltage and fill factor were simultaneously improved due to the optimization of the active layer morphology. The best power conversion efficiency achieved was 3.45% under simulated AM 1.5G illumination of 100 mW/cm², which is an increase of 36% compared to a solar cell without the additive and featuring only P3HT/PCBM as the active layer.     

Incorporation of silver and gold nanostructures for performance improvement in P3HT: PCBM inverted solar cell with rGO/ZnO nanocomposite as an electron transport layer

Inefficient light absorption and inefficient charge separation are considered as two major impediments for the efficiency improvement in bulk heterojunction organic solar cells (BHJ OSCs). In this work, we report the simultaneous role of modified electron transport layer (ETL) and photoactive layers on the performance of poly (3-hexylthiophene), [6, 6]-phenyl C61-butyric acid methyl ester (P3HT: PCBM) BHJ OSCs. To modify the ETL, composite of reduced graphene oxide (rGO) (0.4 wt %) and ZnO nanoparticles (NPs) was used, which resulted in efficiency enhancement from 3.13 to 3.81%, as compared to a value of 3.13% when only ZnO was used. Thereafter, to improve upon the optical absorption properties, the photoactive layer is modified by embedding nanoparticles and nanorods of Ag and Au into it. The size of Ag and Au nanoparticles were chosen to be 50 nm while the dimensions of Ag and Au nanorods were so controlled to obtain length of approx. 50 nm and width of ∼10 nm. All the devices were fabricated in inverted geometry and 20 wt% nanostructures embedded devices showed the best results. For Ag and Au NPs embedded devices, the maximum power conversion efficiency was found to be 4.21% and 4.44%, respectively. On the other hand, for Ag and Au NRs embedded devices, the maximum efficiency was 4.37% and 4.85%, respectively. For comparison, the control devices where no nanostructures were embedded, which shows efficiency of 3.81%. Therefore, an overall enhancement in efficiency was nearly 1.21 and 1.1, 1.16, 1.14, 1.27 fold after modifying ETL as well as the active layer. The reasons for performance improvement were ascribed to better charge extraction properties of ETL, enhanced light absorption due to localized surface plasmon resonance (LSPR) and efficient light scattering by the nanostructures and improved global mobilities.