Influence of chemically p-type doped active organic semiconductor on the film thickness versus performance trend in cyanine/C60 bilayer solar cells

Simple bilayer organic solar cells rely on very thin coated films that allow for effective light absorption and charge carrier transport away from the heterojunction at the same time. However, thin films are difficult to coat on rough substrates or over large areas, resulting in adverse shorting and low device fabrication yield. Chemical p-type doping of organic semiconductors can reduce Ohmic losses in thicker transport layers through increased conductivity. By using a Co(III) complex as chemical dopant, we studied doped cyanine dye/C₆₀ bilayer solar cell performance for increasing dye film thickness. For films thicker than 50 nm, doping increased the power conversion efficiency by more than 30%. At the same time, the yield of working cells increased to 80%. We addressed the fate of the doped cyanine dye, and found no influence of doping on solar cell long term stability.     

Insights into photovoltaic properties of ternary organic solar cells from phase diagrams

The efficiency of ternary organic solar cells relies on the spontaneous establishment of a nanostructured network of donor and acceptor phases during film formation. A fundamental understanding of phase composition and arrangement and correlations to photovoltaic device parameters is of utmost relevance for both science and technology. We demonstrate a general approach to understanding solar cell behavior from simple thermodynamic principles. For two ternary blend systems we construct and model phase diagrams. Details of EQE and solar cell parameters can be understood from the phase behavior. Our blend system is composed of PC₇₀BM, PBDTTT-C and a near-infrared absorbing cyanine dye. Cyanine dyes are accompanied by counterions, which, in a first approximation, do not change the photophysical properties of the dye, but strongly influence the morphology of the ternary blend. We argue that counterion dissociation is responsible for different mixing behavior. For the dye with a hexafluorophosphate counterion a hierarchical morphology develops, the dye phase separates on a large scale from PC₇₀BM and cannot contribute to photocurrent. Differently, a cyanine dye with a TRISPHAT counterion shows partial miscibility with PC₇₀BM. A large two-phase region dictated by the PC₇₀BM: PBDTTT-C mixture is present and the dye greatly contributes to the short-circuit current.     

染料敏化太阳能电池的非金属有机敏化剂

染料敏化太阳能电池(DSSC)是一种新型的太阳能电池,综述了DSSC的非金属有机染料敏化剂的研究现状,分析了各类敏化剂的结构与电池的能量转换效率的关系,并提出非金属有机染料结构的设计思路。     

Investigation of post-thermal annealing-induced enhancement in photovoltaic performance for squaraine-based organic solar cells

In this work, we have systematically investigated the post-thermal annealing-induced enhancement in photovoltaic performance of a 2,4-bis[4-(N, N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine (DIBSQ)/C₆₀ planar heterojunction (PHJ) organic solar cells (OSCs). An increased power conversion efficiency (PCE) of 3.28% has been realized from a DIBSQ/C₆₀ device with thermal annealing at 100 °C for 4 min, which is about 33% enhancement compared with that of the as-cast device. The improvement of the device performance may be mainly ascribed to the crystallinity of the DIBSQ film with post-thermal annealing, which will change the DIBSQ donor and C₆₀ acceptor interface from PHJ to hybrid planar-mixed heterojunction. This new donor–acceptor heterojunction structure will significantly improve the charge separation and charge collection efficiency, as well as the open circuit voltage (V_oc) of the device, leading to an enhanced PCE. This work provides an effective strategy to improve the photovoltaic performance of SQ-based OSCs.     

Highly flexible and transparent conducting silver nanowire/ZnO composite film for organic solar cells

High efficiency and flexible inverted organic solar cells have been fabricated using solution-processed silver nanowire/zinc oxide composite transparent electrodes. The transparent electrodes showed a low sheet resistance of -13 ff）.sq-1 and high transmittance of -93% as well as superior mechanical flexibility. Power conversion efficiencies of -7.57% and -7.21% were achieved for devices fabricated on glass and plastic substrate, respectively. Moreover, the flexible devices did not show any degradation in their performance even after being folded with a radius of-480 μm.     

Influence of thermal annealing-induced molecular aggregation on film properties and photovoltaic performance of bulk heterojunction solar cells based on a squaraine dye

Squaraine (SQ) dyes have been considered as efficient photoactive materials for organic solar cells. In this work, we purposely controlled the molecular aggregation of an SQ dye, 2,4-bis[4-(N,N-dibutylamino)-2-dihydroxyphenyl] SQ (DBSQ-(OH)₂) in the DBSQ(OH)₂:[6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) blend film by using the thermal annealing method, to study the influence of the molecular aggregation on film properties as well as the photovoltaic performance of DBSQ(OH)₂:PCBM-based bulk heterojunction (BHJ) solar cells. Our results demonstrate that thermal annealing may change the aggregation behavior of DBSQ(OH)₂ in the DBSQ(OH)₂:PCBM film, and thus significantly influence the surface morphology, optical and electrical properties of the blend film, as well as the photovoltaic performance of DBSQ(OH)₂:PCBM BHJ cells.     

有序大孔TiO2双层膜的设计合成及其在染料敏化太阳能电池中的应用

以垂直沉积法制备的聚苯乙烯(polystyrene,PS)胶体晶体为模板,钛酸四异丙酯为钛源,通过浸渍-煅烧工艺制备了具有分层次有序结构的大孔TiO2双层膜,并作为光阳极应用于染料敏化太阳能电池(dye-sensitized solar cells,DSSCs)。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、紫外-可见漫反射光谱仪和氮气吸附-脱附分析仪等手段对样品进行了表征。结果表明,有序大孔TiO2薄膜较好地复制了PS模板的三维有序结构,且有较大的比表面积。光电性能测试结果表明,与以纯P25薄膜为光阳极的DSSCs相比,有序大孔TiO2双层膜为光阳极能够明显提高DSSCs的光电转换效率,可从4.16%提高到6.08%。该类型分层次有序结构大孔TiO2双层膜在DSSCs中具有重要的潜在应用价值。     

碘盐对聚合物凝胶电解质及染料敏化太阳电池性能的影响

通过简单方法合成了一种新型有机碘盐N-甲基吡啶碘，以苯乙烯-丙烯腈共聚物（AS树脂）为聚合物凝胶电解质基体，丙烯碳酸酯及乙烯碳酸酯双组分有机溶剂为液相，制备了含有机碘盐（N-甲基吡啶碘）和无机碘盐（NaI）的AS树脂基聚合物凝胶电解质，比较了两种碘盐对聚合物凝胶电解质导电性能及染料敏化纳米晶太阳电池光电性能的影响，发现含有机碘盐的聚合物凝胶电解质具有较高的电导率，所制备的DSSC光电性能也较好。     

The effects of the thickness of TiO2 films on the performance of dye-sensitized solar cells

Nanocrystalline anatase TiO₂ thin films with different thicknesses (0.5-2.0 μm) have been deposited on ITO-coated glass substrates by a sol-gel method and rapid thermal annealing for application as the work electrode for dye-sensitized solar cells (DSSC). From the results, the increases in thickness of TiO₂ films can increase adsorption of the N3 dye through TiO₂ layers to improve the short-circuit photocurrent (J_sc) and open-circuit voltage (V_oc), respectively. However, the J_sc and V_oc of DSSC with a TiO₂ film thickness of 2.0 μm (8.5 mA/cm² and 0.61 V) are smaller than those of DSSC with a TiO₂ film thickness of 1.5 μm (9.2 mA/cm² and 0.62 V). It could be due to the fact that the increased thickness of TiO₂ thin films also resulted in a decrease in the transmittance of TiO₂ thin films thus reducing the incident light intensity on the N3 dye. An optimum power conversion efficiency (η) of 2.9% was obtained in a DSSC with the TiO₂ film thickness of 1.5 μm.     

基于P3HT的有机太阳能电池的特性研究

聚3已基噻吩（P3HT）是近年来出现的一种新型有机聚合物太阳能电池的供电子体材料。通过真空蒸镀与旋涂相结合的方法,制备了基于聚合物P3HT的结构为ITO/Buffer layer/P3HT/C60/Bphen/Ag的有机太阳能电池。测试结果表明P3HT、C60的优化厚度分别为30、40nm。如果还引入金属氧化物MoO3作为阳极缓冲层,能够明显地提高电池的开路电压,其中MoO3阳极缓冲层的优化厚度为1nm。因此,通过优化制备工艺、引入新的器件材料,能更理想地调控太阳能电池的性能参数。     

Effects of film treatment on the performance of poly(3-hexylthiophene)/soluble fullerene-based organic solar cells

This work investigates the correlations between the morphological characteristics of the active layers, comprised of poly(3-hexylthiophene) and [6,6]-phenyl-C₆₁-butyric acid methyl ester, and the photovoltaic performance of polymer-based solar cells. The active layers were deposited by spin-coating the polymer solutions under various conditions and, then, characterized by atomic force microscopy, X-ray diffraction, UV/Vis and Raman spectroscopy. Results of this study indicate that solar cells employing the slow-solvent-vapor-treatment blend films as the active layers exhibit the enhanced power conversion efficiency (3.0%), short-circuit (8.71 mA/cm²) current and fill factor (0.59) than that of as-cast and fast-thermal-annealing blend films.     

The influence of base doping density on the performance of evaporated poly-Si thin-film solar cells by solid-phase epitaxy

The phosphorous base doping dependence of evaporated poly-Si thin-film solar cell by aluminium-induced crystallization solid-phase epitaxy (ALICE) has been investigated. It is found that the open-circuit voltage (V_oc) of the the poly-Si thin-film solar cell increases with the decrease of base doping density due to the defect-rich nature of poly-Si thin-film material and effectiveness of the back surface field. Meanwhile, the short-circuit current (J_sc) also increases with the decrease of the base doping density as a result of the reduced doping-induced defects. Therefore, the maximum V_oc and J_sc are simultaneously achieved when the lowest phosphorous base doping density (~ 5.5 × 10¹⁵ cm^− 3) is applied.     

CuPc/C60薄膜太阳能电池的制备及膜厚对其光电性能的影响

本文采用CuPc作为电子给体,C60作为电子受体制备了ITO/CuPc/C60/Al异质结太阳能电池。实验表明器件中活性层(CuPc/C60)对太阳能电池的光电性能有很大的影响。主要原因是有机物的激子扩散长度大约是十几纳米左右,产生的激子大多数在未到达异质结之前就已经复合。本文讨论了活性层(CuPc/C60)的厚度比,并获得其最优比例。     

掺杂材料对蓝光OLED器件性能的影响

采用ADN作为主体材料, 并且对其使用NPB、BAlq3和TBP等材料进行掺杂,制备了一系列蓝光OLED,研究了掺杂对器件性能的影响.实验结果表明,掺杂NPB的器件由于载流子注入和传输趋向平衡,其光电性能明显优于未掺杂的器件; 掺杂BAlq3的器件则具有最佳的色纯度,CIE坐标为(0.15,0.18); 而掺杂TBP的器件则具有高效的能量传递,其流明效率和电流效率分别达到了1.43 lm/W和3.86 cd/A,发光寿命最长,并具有较窄的发光光谱,其色纯度为(0.18,0.19).这些结果说明掺杂不仅改善了器件的发光亮度和色纯度, 而且提高了器件的发光效率和寿命.     

Influence of anode roughness and buffer layer nature on organic solar cells performance

Fluorine doped transparent conductive tin oxide thin films (FTO) of different surface roughness have been deposited by chemical vapor deposition (FTO_SOL), classical chemical spray pyrolysis (FTO_CSP), and spray pyrolysis onto heated substrates using infra red irradiation (FTO_IRSP); the three deposition methods inducing different surface roughness. It was found that the different FTOs presented similar electrical properties while their structural, morphological and optical properties were related to surface properties. These FTO films have been used as anode in multilayer organic solar cells, based on coupled donor/acceptor-copper phthalocyanine/fullerene. To improve solar cell performance, buffer layers of different natures have been tried at the anode/organic material interface. Deposition of a thin molybdenum oxide film onto FTO smooth films afforded reproducible devices with performance similar to those obtained with indium tin oxide anodes. However, cell efficiency decreased as FTO surface roughness increased. The degree of degradation depended on the nature of the buffer layer. We show that it is necessary to use buffer layer material that allows consistency and completeness of the electrode coverage.     

SrCO_3/TiO_2复合薄膜太阳能电池的性能研究

采用丝网印刷法制备了SrCO3/TiO2复合薄膜电极;组装电池,研究了复合电极的光电性能。结果表明:敏化SrCO3/TiO2复合薄膜电极太阳能电池的短路电流密度、开路电压和填充因子比敏化TiO2电极电池均有增加,总的光电转换效率从3.01%提高到了3.53%,增加了17.3%。另外紫外光谱表明,SrCO3/TiO2复合薄膜电极吸附更多的染料。电化学阻抗谱研究表明,SrCO3/TiO2复合薄膜电极相对于空白TiO2电极有更小的阻抗,有利于电子在薄膜中的传输,提高了太阳能电池的性能。     

聚苯乙烯和聚乙二醇对TiO2薄膜微观结构及DSSC性能的影响

用水热法制备了多孔TiO2光电薄膜;分析了聚苯乙烯和聚乙二醇对纳米TiO2晶体薄膜微观结构的影响;用紫外-可见-近红外分光光度计和场发射扫描电镜对纳米TiO2薄膜进行了表征;并对组装的染料敏化太阳能电池进行了光电性能测试,发现用聚苯乙烯处理后的TiO2薄膜提高了染料敏化太阳能电池(DSSC)的开路电压、短路电流密度、填充因子和光电转换效率.     

Influence of annealing on p-type Cu2ZnSnS4 thin film by dip coating solution growth technique for the application of solar cell

Thin films of Cu₂ZnSnS₄ have been deposited by solution growth dip coating method. Different Cu/Zn/Sn/S molar ratios were applied, which tells the properties of copper, Zinc, Tin, and Sulfide using X-ray diffraction, UV–vis, Energy dispersive X-ray spectroscopy, and scanning electron spectroscopy. The pure CZTS thin film showed the phase transformation from Kesterite (tetragonal) to Kesterite (orthorhombic) crystal structure. Optical measurement analysis reveals that layers have relatively high absorption coefficient in the visible spectrum with a band gap reduction of 1.51–1.49?eV with an increase in the annealing temperature from room temperature to 300?°C for 1?h in hot air furnace without any presence of an inert gas. Optical conductivity was observed to increase from 10¹² to 10¹³ (sec)^?1 and electrical conductivity was of the order of 10² (Ω?cm)^?1.     

Transfer-printing of active layers to achieve high quality interfaces in sequentially deposited multilayer inverted polymer solar cells fabricated in air

Polymer solar cells (PSCs) are greatly influenced by both the vertical concentration gradient in the active layer and the quality of the various interfaces. To achieve vertical concentration gradients in inverted PSCs, a sequential deposition approach is necessary. However, a direct approach to sequential deposition by spin-coating results in partial dissolution of the underlying layers which decreases the control over the process and results in not well-defined interfaces. Here, we demonstrate that by using a transfer-printing process based on polydimethylsiloxane (PDMS) stamps we can obtain increased control over the thickness of the various layers while at the same time increasing the quality of the interfaces and the overall concentration gradient within the active layer of PSCs prepared in air. To optimize the process and understand the influence of various interlayers, our approach is based on surface free energy, spreading parameters and work of adhesion calculations. The key parameter presented here is the insertion of high quality hole transporting and electron transporting layers, respectively above and underneath the active layer of the inverted structure PSC which not only facilitates the transfer process but also induces the adequate vertical concentration gradient in the device to facilitate charge extraction. The resulting non-encapsulated devices (active layer prepared in air) demonstrate over 40% increase in power conversion efficiency with respect to the reference spin-coated inverted PSCs.