Synthesis of ZnO nanorods and their application in quantum dot sensitized solar cells

ZnO nanorod thin films of different thicknesses and CdS quantum dots have been prepared by chemical method. X-ray diffraction pattern reveals that the CdS quantum dot and ZnO nanorods are of hexagonal structure. Field emission scanning electron microscope images show that the diameter of hexagonal shaped ZnO nanorods ranges from 110 to 200 nm and the length of the nanorod vary from 1.3 to 4.7 μm. CdS quantum dots with average size of 4 nm have been deposited onto ZnO nanorod surface using successive ionic layer adsorption and reaction method and the assembly of CdS quantum dot with ZnO nanorod has been used as photo-electrode in quantum dot sensitized solar cells. The efficiency of the fabricated CdS quantum dot-sensitized ZnO nanorod-based solar cell is 1.10 % and is the best efficiency reported so far for this type of solar cells.     

Nanocrystalline TiO2 solar cells sensitized with InAs quantum dots

We report nanocrystalline TiO2 solar cells sensitized with InAs quantum dots. InAs quantum dots of different sizes were synthesized and incorporated in solar cell devices. Efficient charge transfer from InAs quantum dots to TiO2 particles was achieved without deliberate modification of the quantum dot capping layer. A power conversion efficiency of about 1.7% under 5 mW/cm2 was achieved; this is relatively high for a nanocrystalline metal oxide solar cell sensitized with presynthesized quantum dots, but this efficiency could only be achieved at low light intensity. At one sun, the efficiency decreased to 0.3%. The devices are stable for at least weeks under room light in air.     

Unpredicted electron injection in CdS/CdSe quantum dot sensitized ZrO2 solar cells

A quantum dot sensitized solar cell based on a porous ZrO(2) film, sensitized with CdSe quantum dots using CdS as an intermediate layer is presented. We observe electron injection from photo-excited quantum dots into the ZrO(2), which is unexpected due to the much higher conduction band edge (closer to the vacuum level) of bulk ZrO(2) compared to TiO(2).     

Electrophoretic Deposition of a Reduced Graphene–Au Nanoparticle Composite Film as Counter Electrode for CdS Quantum Dot‐Sensitized Solar Cells

A reduced graphene (RG)‐Au nanoparticle composite film is successfully fabricated by electrophoretic deposition and used as counter electrode for quantum dot‐sensitized solar cells. The RG‐Au composite is prepared by one‐step microwave‐assisted reduction of chloroaurate in alkaline solution with graphite oxide dispersion. Under one sun illumination (AM 1.5 G, 100 mW cm^?2), the cell with a RG‐Au counter electrode shows an energy conversion efficiency of 1.36 %, which is higher than those of cells employing conventional Pt or Au counter electrodes, due to the superior combination of highly catalytic Au nanoparticles and the conductive graphene network structure.     

Light conversion efficiency of flower like structure TiO<Subscript>2</Subscript> thin film solar cells

Flower like structure TiO₂ thin films have been grown onto ITO coated glass substrates by sol–gel method. TiO₂ nano flowers have been sensitized using CdS quantum dots prepared using simple precursors by chemical method. The assembly of CdS quantum dots with TiO₂ nano flower has been used as photo-electrode in quantum dot sensitized solar cells. The surface morphology has been studied using scanning electron microscope; it shows that the film exhibits flower like structure. The absorption spectra reveals that the absorption edge of CdS quantum dot sensitized TiO₂ nano flower shifts towards longer wavelength side when compared to the absorption edge of TiO₂ nano flower. The efficiency of the fabricated CdS quantum dot sensitized TiO₂ nano flower based solar cell is 0.66%.     

Highly efficient,PbS:Hg quantum dot–sensitized,plasmonic solar cells with TiO2 triple-layer photoanode

Journal of Solid State Electrochemistry - Highly efficient, PbS:Hg quantum dot–sensitized, plasmonic solar cells with TiO2 triple-layer photoanode were fabricated by successive ionic layer...     

Graphene quantum dots assisted photovoltage and efficiency enhancement in CdSe quantum dot sensitized solar cells

CdSe quantum dot sensitized solar cells(QDSCs) modified with graphene quantum dots(GQDs) have been successfully achieved in this work for the first time. Satisfactorily, the optimized photovoltage(Voc) of the modified QDSCs was approximately 0.04 V higher than that of plain CdSe QDSCs, consequently improving the photovoltaic performance of the resulting QDSCs. Served as a novel coating on the CdSe QD sensitized photoanode, GQDs played a vital role in improving Vocdue to the suppressed charge recombination which has been confirmed by electron impedance spectroscopy as well as transient photovoltage decay measurements. Moreover, different adsorption sequences, concentration and deposition time of GQDs have also been systematically investigated to boost the power conversion efficiency(PCE) of CdSe QDSCs. After the coating of CdSe with GQDs, the resulting champion CdSe QDSCs exhibited an improved PCE of 6.59% under AM 1.5G full one sun illumination.     

Fortification of CdSe quantum dots with graphene oxide. Excited state interactions and light energy conversion

Graphene based 2-D carbon nanostructures provide new opportunities to fortify semiconductor based light harvesting assemblies. Electron and energy transfer rates from photoexcited CdSe colloidal quantum dots (QDs) to graphene oxide (GO) and reduced graphene oxide (RGO) were isolated by analysis of excited state deactivation lifetimes as a function of degree of oxidation and charging in (R)GO. Apparent rate constants for energy and electron transfer determined for CdSe-GO composites were 5.5 × 10(8) and 6.7 × 10(8) s(-1), respectively. Additionally, incorporation of GO in colloidal CdSe QD films deposited on conducting glass electrodes was found to enhance the charge separation and electron conduction through the QD film, thus allowing three-dimensional sensitization. Photoanodes assembled from CdSe-graphene composites in quantum dot sensitized solar cells display improved photocurrent response (~150%) over those prepared without GO.     

Quantum Dot Sensitized Solar Cell: Photoanodes,Counter Electrodes,and Electrolytes

In this study, we provide the reader with an overview of quantum dot application in solar cells to replace dye molecules, where the quantum dots play a key role in photon absorption and excited charge generation in the device. The brief shows the types of quantum dot sensitized solar cells and presents the obtained results of them for each type of cell, and provides the advantages and disadvantages. Lastly, methods are proposed to improve the efficiency performance in the next researching.     

A Solar Cell That Is Triggered by Sun and Rain

All‐weather solar cells are promising in solving the energy crisis. A flexible solar cell is presented that is triggered by combining an electron‐enriched graphene electrode with a dye‐sensitized solar cell. The new solar cell can be excited by incident light on sunny days and raindrops on rainy days, yielding an optimal solar‐to‐electric conversion efficiency of 6.53 % under AM 1.5 irradiation and current over microamps as well as a voltage of hundreds of microvolts by simulated raindrops. The formation of π‐electron|cation electrical double‐layer pseudocapacitors at graphene/raindrop interface is contributable to current and voltage outputs at switchable charging–discharging process. The new concept can guide the design of advanced all‐weather solar cells.     

CdS量子点敏化ZnO纳米棒阵列电极的制备和光电化学性能

采用连续式离子层吸附与反应法制备了CdS量子点敏化的ZnO纳米棒电极.应用扫描电子显微镜(SEM)、X射线衍射(XRD)和透射电子显微镜(TEM)对CdS量子点/ZnO纳米棒电极的形貌、晶型和颗粒尺寸进行了分析和表征;采用光电流-电位曲线和光电流谱研究了不同CdS循环沉积次数及不同沉积浓度对复合电极的光电性能影响.结果表明,前驱体浓度都为0.1mol·L-1且沉积15次敏化后的ZnO纳米棒阵列电极光电性能最好.与单纯的ZnO纳米棒阵列电极和单纯的CdS量子点电极相比,其光电转换效率显著提高,单色光光子-电流转换效率(IPCE)在380nm处达到76%.这是因为CdS量子点可以拓宽光的吸收到可见光区,并且在所形成的界面上光生载流子更容易分离.荧光光谱实验进一步说明了光电增强的原因是,两者间形成的界面中表面态大大减少,有利于减少光生电子和空穴的复合.     

Biomass‐Derived Carbon Quantum Dot Sensitizers for Solid‐State Nanostructured Solar Cells

New hybrid materials consisting of ZnO nanorods sensitized with three different biomass‐derived carbon quantum dots (CQDs) were synthesized, characterized, and used for the first time to build solid‐state nanostructured solar cells. The performance of the devices was dependent on the functional groups found on the CQDs. The highest efficiency was obtained using a layer‐by‐layer coating of two different types of CQDs.     

温度对多硫电解质及量子点敏化太阳能电池性能的影响

采用电化学的方法研究了温度对多硫电解质导电性能及量子点敏化太阳能电池光电性能的影响.结果表明:随着温度的升高,电解质的电导率逐步升高,多硫离子在电解质中的扩散阻力变小;另外,随着温度的升高,量子点敏化太阳能电池的光电转化效率逐渐降低,这主要是由于在较高的温度下,电池的暗反应逐渐增大和量子点的脱附引起的.     

Characterization and Polymerization of Thienylphenyl and Selenylphenyl Amines and Their Interaction with CdSe Quantum Dots

Hybrid quantum‐dot‐sensitized solar cells show promising novel optoelectronic properties. An adequate design of such cells requires a deep understanding of the characteristics of each component, including their interactions. In this context, the electrochemical properties of two different hole‐transporting materials (HTMs) and their chemical interactions with trioctylphosphine‐capped CdSe quantum dots are investigated to evaluate their potential use in hybrid quantum‐dot‐sensitized solar cells. Tris[4‐(thien‐2‐yl)phenyl]amine (TTPA) and tris[4‐(selen‐2‐yl)phenyl]amine (TSePA) are studied in the solid state as thin films deposited on a conducting substrate. Spectroelectrochemical studies evidence both solid‐state electropolymerization and doping. Upon addition of TSePA or partially polymerized TTPA to a colloidal solution of trioctylphosphine‐capped CdSe quantum dots, the steady‐state photoluminescence is quenched. This suggests that the quantum dots and the HTM strongly interact, probably through an excited‐state charge‐transfer mechanism. The combination of all these pieces of information indicates that polymerized TTPA and TSePA are potential candidates as HTMs for hybrid quantum‐dot‐sensitized solar cells.     

Easily manufactured TiO2 hollow fibers for quantum dot sensitized solar cells

TiO(2) hollow fibers with high surface area were manufactured by a simple synthesis method, using natural cellulose fibers as template. The effective light scattering properties of the hollow fibers, originating from their micron size, were observed by diffuse reflectance spectroscopy. In spite of the micrometric length of the TiO(2) hollow fibers, the walls were highly porous and high surface area (78.2 m(2) g(-1)) was obtained by the BET method. TiO(2) hollow fibers alone and mixed with other TiO(2) pastes were sensitized with CdSe quantum dots (QDs) by Successive Ionic Layer Adsorption and Reaction (SILAR) and integrated as a photoanode in quantum dot sensitized solar cells (QDSCs). High power conversion efficiency was obtained, 3.24% (V(oc) = 503 mV, J(sc) = 11.92 mA cm(-2), FF = 0.54), and a clear correspondence of the cell performance with the photoanode structure was observed. The unique properties of these fibers: high surface area, effective light scattering, hollow structure to facile electrolyte diffusion and the rather high efficiencies obtained here suggest that hollow fibers can be introduced as promising nanostructures to make highly efficient quantum dot sensitized solar cells.     

Numerical Investigation of Graphene as a Back Surface Field Layer on the Performance of Cadmium Telluride Solar Cell

This paper numerically explores the possibility of ultrathin layering and high efficiency of graphene as a back surface field (BSF) based on a CdTe solar cell by Personal computer one-dimensional (PC1D) simulation. CdTe solar cells have been characterized and studied by varying the carrier lifetime, doping concentration, thickness, and bandgap of the graphene layer. With simulation results, the highest short-circuit current (I_sc = 2.09 A), power conversion efficiency (η = 15%), and quantum efficiency (QE~85%) were achieved at a carrier lifetime of 1 × 10³ μs and a doping concentration of 1 × 10¹⁷ cm⁻³ of graphene as a BSF layer-based CdTe solar cell. The thickness of the graphene BSF layer (1 μm) was proven the ultrathin, optimal, and obtainable for the fabrication of high-performance CdTe solar cells, confirming the suitability of graphene material as a BSF. This simulation confirmed that a CdTe solar cell with the proposed graphene as the BSF layer might be highly efficient with optimized parameters for fabrication.     

4.81%光电转换效率的全固态致密PbS量子点薄膜敏化TiO2纳米棒阵列太阳电池

A compact PbS quantum-dot thin film was prepared using the combination of TiO₂ nanorod arrays and 1, 2-ethanedithiol following the spin-coating assisted successive ionic layer absorption and reaction procedure. Solar cells with the novel structure of FTO/compact PbS quantum-dot thin film sensitized TiO₂ nanorod arrays/spiro-OMeTAD/Au were assembled. Subsequently, the influence of the length of TiO₂ nanorod arrays on the photovoltaic performance of all-solid-state compact PbS quantum-dot thin film sensitized solar cells was evaluated. The corresponding solar cells having TiO₂ nanorod array lengths of 290, 540, and 1040 nm achieved photoelectric conversion efficiencies (PCE) of 2.02%, 4.81%, and 1.95%, respectively. These results reveal that in order to achieve high PCE values with the all-solid-state quantum dot sensitized solar cells, it is very important to balance the hole diffusion length with the loading amount of quantum-dots.     

A solid-state CdSe quantum dot sensitized solar cell based on a quaterthiophene as a hole transporting material

A hybrid quantum dot sensitized solar cell (QDSC) composed of CdSe quantum dots (QDs) as light harvesters and TiO(2) and 3,3'-didodecyl-quaterthiophene (QT12) as electron and hole conductors, respectively, has been fully processed in air. The sensitizer has been introduced into the TiO(2) nanoporous layer either by the successive ionic layer adsorption and reaction method or by attaching colloidal QDs either directly or through molecular cables (linkers). As previously observed for QDSCs based on liquid electrolytes, the efficiency depends on the way of QD attachment, the direct adsorption of QDs being the procedure yielding the best results. Thermal annealing was applied in order to enhance the device response under illumination. Remarkable open circuit potentials are attained (close to 1 V), leading to an efficiency of 0.34% (AM 1.5G) in initial tests. Although low, it ranks as one of the highest values reported for solid state QDSCs based on titanium dioxide and colloidal quantum dots.     

基于量子点涂料的柔性光阳极及碳基对电极的制备和优化

首先制备出量子点(QDs)/TiO_2涂料,分别采用丝网印刷法与刀刮法将涂料涂覆于ITO/PET柔性基底上,结果表明刀刮法制备量子点敏化太阳电池(QDSCs)效果更佳,且具有普适性。基于铜片对电极所组装的ZnCuInSe,CdSe和CdSeTe量子点半柔性QDSCs最高效率分别达2.83%,2.46%和1.99%。另外,我们对石墨纸进行表面化学修饰以提高亲水性,再通过简单的连续离子交换吸附法(SILAR)在石墨纸上负载Cu_xS纳米粒子,制备出Cu_xS/GP柔性对电极,进一步组装成全柔性QDSCs,获得了2.13%光电转化效率。     

基于量子点涂料的柔性光阳极及碳基对电极的制备和优化

首先制备出量子点（QDs）/TiO₂涂料,分别采用丝网印刷法与刀刮法将涂料涂覆于ITO/PET柔性基底上,结果表明刀刮法制备量子点敏化太阳电池（QDSCs）效果更佳,且具有普适性。基于铜片对电极所组装的ZnCuInSe,CdSe和CdSeTe量子点半柔性QDSCs最高效率分别达2.83%,2.46%和1.99%。另外,我们对石墨纸进行表面化学修饰以提高亲水性,再通过简单的连续离子交换吸附法（SILAR）在石墨纸上负载Cu_xS纳米粒子,制备出Cu_xS/GP柔性对电极,进一步组装成全柔性QDSCs,获得了2.13%光电转化效率。