Al纳米颗粒增强微晶硅薄膜太阳电池光吸收的模拟研究

利用价格低廉、性能优良的金属纳米颗粒增强太阳电池的光吸收具有广阔的应用前景. 通过建立三维数值模型, 模拟了微晶硅薄膜电池前表面周期性分布的Al纳米颗粒阵列对电池光吸收的影响, 并对其结构参数进行了优化. 模拟结果表明: 对于球状Al纳米颗粒阵列, 影响电池光吸收的关键参数是周期P与半径R的比值, 或者说是颗粒的表面覆盖度; 当P/R=4–5时, 总的光吸收较参考电池提高可达20%. 与球状颗粒相比, 优化后的半球状Al纳米颗粒阵列可获得更好的陷光效果, 但后者对颗粒半径R的变化较敏感. 另外, 结合电场分布, 对电池光吸收增强的物理机理进行了分析.     

Control of the input efficiency of photons into solar cells with plasmonic nanoparticles

We study numerically the photon input efficiency of silicon solar cells due to gold plasmonic nanoparticles deposited on the cells. At low densities, when collective effects in light scattering by the nanoparticle ensemble are negligible, the absorption dependence increases linearly for a significant range of the solar spectrum. Collective effects lead to the input efficiency saturates, reaches its maximum and then decreases with nanoparticle density. The maximal input efficiency depends on the photon wavelength, nanoparticle shape and size, their distance to the cell, and the cell thickness, and can reach ~ 95% in thick solar cells. Finally, we show that aluminum nanoparticles improve the input efficiency in comparison with gold nanoparticles.     

银纳米颗粒减反射特性的理论研究

为增强晶体硅太阳电池的光利用效率,提高光电转换效率,研究了金属银纳米颗粒的光学散射性质.基于银纳米粒子表面等离子激元效应和MIE散射理论,采用Matlab数值计算,理论分析了不同银纳米颗粒尺寸和银粒子分布密度对太阳光谱各波长的散射特性.获得了实现高的光透过率所需最佳银纳米颗粒半径范围,研究发现随着银纳米颗粒半径增加,偶极峰红移、高极峰逐渐出现.定量地给出了最佳颗粒分布密度随银粒子半径的变化规律,建立了计算减反射膜透射率的理论方法,找到了银纳米颗粒光学透过率的简单函数表达式,能为实验研究提供理论指导. 关键词： 银纳米颗粒 透过率 MIE理论 太阳电池     

非晶硅太阳电池宽光谱陷光结构的优化设计

陷光是改善薄膜太阳电池光吸收进而提高其效率的关键技术之一. 以非晶硅（α-Si）薄膜太阳电池为例,设计了一种新的复合陷光结构：在Ag背电极与硅薄膜之间制备一维Ag纳米光栅,并通过保形生长在电池前表面沉积织构的减反膜. 采用有限元数值模拟方法,研究了该复合陷光结构对电池光吸收的影响,并对Ag纳米光栅的结构参数进行了优化. 模拟结果表明：该复合陷光结构可在宽光谱范围内较大地提高太阳电池的光吸收;当Ag纳米光栅的周期P为600 nm,高度H为90 nm,宽度W为180 nm时,在AM1.5光谱垂直入射条件下α-Si薄膜电池在300–800 nm波长范围内总的光吸收较无陷光结构的参考电池提高达103%,其中在650–750 nm长波范围内的光子吸收率提高达300%以上. 结合电场强度分布,对电池在各个波段光吸收提高的物理机制进行了分析. 另外,该复合陷光结构的引入,还较大地改善了非晶硅电池对太阳光入射角度的敏感性. 关键词： 非晶硅太阳电池 陷光 银纳米光栅 数值模拟     

非晶硅光伏电池表面高效光陷阱结构设计

提出一种应用于非晶硅光伏电池表面的光陷阱结构,该结构主要由衍射光栅、低折射率MgF₂膜层、高折射率ZnS膜层及金属Ag反射镜组成.在标准测试条件(AM1.5,100 mW/cm²和25 ℃)下,运用严格耦合波理论,通过计算400-1000 nm波段内的1 μm厚非晶硅光伏电池的吸收光子数加权平均ξ_AM1.5,优化光陷阱结构的设计参数.结果表明:对于电池前表面减反射结构,在衍射光栅周期为800 nm、高度为160 关键词： 光陷阱结构 衍射光栅 减反射膜 非晶硅光伏电池     

Highly crystallized sputtered silicon with textured morphology for thin-film solar cells

A light-trapping structure with textured morphology for thin-film solar cell is demonstrated in this paper. It is fabricated through Al evaporation, and has a root-mean-roughness (Rms) of about 120 nm and lateral width of about 1 μm for single bulge. A Mo layer is introduced to be a barrier layer. Subsequently sputtered amorphous silicon film is 100% crystallized by Cu induced crystallization. Reflectivity of samples with different silicon thickness is studied to reveal the light-trapping efficiency and the reflectivity as low as 10% is obtained with only 840 nm thick silicon film. This is a low-cost structure promising for future thin-film solar cells with high efficiency.     

Solar cell performance improvement via photoluminescence conversion of Si nanoparticles

Photoluminescence (PL) conversion of Si nanoparticles by absorbing ultraviolet (UV) lights and emitting visible ones has been used to improve the efficiency of crystalline Si solar cells. Si nanoparticle thin films are prepared by pulverizing porous Si in ethanol and then mixing the suspension with a SiO2 sol-gel (SOG).This SOG is spin-deposited onto the surface of the Si solar cells and dries in air. The short-circuit current as a function of Si nanoparticle concentration is investigated under UV illumination. The maximal increase is found at a Si concentration of 0.1 mg/mL. At such concentration and under the irradiation of an AM0 solar simulator, the photoelectric conversion efficiency of the crystalline Si solar cell is relatively increased by 2.16% because of the PL conversion.     

New issue of GaN nanoparticles solar cell

This study involves the synthesis of gallium nitride (GaN) nanoparticles (NPs) under different low temperatures using a simple chemical method. The nanoparticles are spin coated on Si substrate to fabricate the solar cell. The FESEM images obtained indicate the presence of cubic GaN nanoparticle with average diameter of 50 nm synthesized at 90 °C. The spin coating technique deposited n-GaN NPs/Si(111) produced a heterojunction solar cell with fill factor of 0.56 and conversion efficiency of 2.06%. Based on these results, this study proposes a novel low cost technique for the fabrication of GaN NPs solar cells.     

TiO_2 composite electron transport layers for planar perovskite solar cells by mixed spray pyrolysis with precursor solution incorporating TiO_2 nanoparticles

Perovskite solar cells with planar structure are attractive for their simplified device structure and reduced hysteresis effect. Compared to conventional mesoporous devices, TiO_2 porous scaffold layers are removed in planar devices. Then,compact TiO_2 electron transport layers take the functions of extracting electrons, transporting electrons, and blocking holes.Therefore, the properties of these compact TiO_2 layers are important for the performance of solar cells. In this work, we develop a mixed spray pyrolysis method for producing compact TiO_2 layers by incorporating TiO_2 nanoparticles with different size into the precursor solutions. For the optimized nanoparticle size of 60 nm, a power conversion efficiency of 16.7% is achieved, which is obviously higher than that of devices without incorporated nanoparticles(9.9%). Further investigation reveals that the incorporation of nanoparticles can remarkably improve the charge extraction and recombination processes.     

Nano Ag-enhanced photoelectric conversion efficiency in all-inorganic,hole-transporting-layer-free CsPbIBr2 perovskite solar cells

All-inorganic, hole-transporting-layer-free CsPbIBr₂ perovskite solar cells have great potential for development, but their device performance needs to be further improved. Recently, metal nanostructures have been successfully applied in the field of solar cells to improve their performance. Nano Ag-enhanced power conversion efficiency (PCE) in one CsPbIBr₂ perovskite solar cell utilizing localized surface plasmons of Ag nanoparticles (NPs) on the surface has been researched experimentally and by simulation in this paper. The localized surface plasmon resonance of Ag NPs has a near-field enhancement effect, which is expected to improve the light absorption of CsPbIBr₂ perovskite photovoltaic devices. In addition, Ag NPs have a forward-scattering effect on the incident light, which can also improve the performance of CsPbIBr₂-based perovskite photovoltaic devices. By directly assembling Ag NPs (with a size of about 150 nm) on the surface of fluorine-doped tin oxide it is found when the particle surface coverage is 10%, the CsPbIBr₂ perovskite photovoltaic device achieves a best PCE of 2.7%, which is 9.76% higher than that of the control group. Without changing any existing structure in the ready-made solar cell, this facile and efficient method has huge applications. To the best of our knowledge, this paper is the first report on nano Ag-enhanced photoelectric conversion efficiency in this kind of CsPbIBr₂ perovskite solar cell.     

Photovoltaic characteristics of hybrid MEH-PPV-nanoparticles compound

Organic solar cell research has vastly developed in recent years. These organic solar cells however are still limited to low power conversion efficiencies. This has led to the generation of photovoltaic cells based on hybrid nanoparticle-organic polymer materials. The hybrid solar cell has the potential of bridging the efficiency gap which is present in organic and inorganic semiconductor materials. This paper focuses on characterization of fabricated hybrid active layer consisting of organic polymer infused with semiconductor nanoparticles. The active layer was deposited on the substrate using the spin coating technique. Materials used in the active layer are poly (2-methoxy, 5-(2-ethyl hexyloxy) p-phenyl vinylene) MEH-PPV, cadmium telluride (CdTe) and cadmium sulphide (CdS). The fabricated solar cells with active layer of MEH-PPV only were found to have a power conversion efficiency of 0.1% for 1 W, hybrid cell with active layer of MEH-PPV/CdTe has power conversion efficiency of 0.15% for 1 W and hybrid cell with active layer of MEH-PPV/CdTe/CdS has power conversion efficiency of 0.18% for 1 W.     

Improved efficiency of small-molecular (S-M) tandem organic solar cells (TOSCs) by employing low work function alloy nanoparticle intermediate layer

We improved the power conversion efficiency (PCE) of the small molecular (S-M) tandem organic solar cells (TOSCs) by employing different low work function alloy nanoparticle intermediate layers. The enhancement of the PCE was mainly attributed to the gap states formed at the interface between the buffer layer and alloy nanoparticle intermediate layer. The gap states result in the disappearance of the electron injection barrier. Compared with the planar heterojunction (PHJ) TOSCs with single Ag nanoparticle intermediate layer, the PCE of the PHJ TOSC with the Mg-Ag alloy nanoparticle intermediate layer exhibits an enhancement of 7.5%. Moreover, the Mg-Ag alloy nanoparticle intermediate layer was also employed in the bulk-heterojunction (BHJ) TOSCs. Compared with the PHJ TOSCs, the PCE of the BHJ TOSCs with Mg-Ag alloy nanoparticle intermediate layer is doubled and achieves a value of 5.54%.     

Gas sensing behavior of SnO1.8:Ag films composed of size-selected nanoparticles

Size-selected SnO_1.8:Ag mixed nanoparticle films have been prepared using a gas phase condensation method. Transmission electron microscopy showed that the applied size-selection technique yields well-defined, monodisperse and spherical SnO_1.8 and Ag nanoparticles, both with a fixed diameter of 20 nm. The technique allows an independent variation of the particle size of both materials as well as the concentration of Ag. It allows to assess the influence of these parameters on the gas-sensing properties of the films, here for ethanol vapor in synthetic air. SnO_1.8:Ag nanoparticle films show optimal values of the sensor signal and response time at a Ag nanoparticle concentration of 5%. Due to the fact that the Ag nanoparticles are clearly distinct from the SnO_1.8 nanoparticles in the film, the most probable mechanism leading to improved sensor properties is chemical sensitization via a spill-over effect.     

Dual plasmonic‐enhanced bulk‐heterojunction solar cell incorporating gold nanoparticles into solution‐processed anode buffer layer and active layer

A dual plasmonic resonance effect on the performance of poly(3‐hexylthiophene) (P3HT):phenyl C61‐butyricacid methyl ester (PC61BM) based polymer solar cells (PSCs) has been demonstrated by selectively incorporating 25 nm colloidal gold nanoparticles (Au NPs) in a solution‐processed molybdenum oxide (MoO₃) anode buffer layer and 5 nm colloidal Au NPs in the active P3HT:PCBM layer. The devices exhibit up to ～20% improvement in power conversion efficiency which is attributed to the dual effect of localized surface plasmon resonance (LSPR) of Au NPs with enhanced light absorption and exciton generation. Our report shows a guideline on the usage of dual LSPR effect for the solution‐processed polymer solar cells to achieve high efficiencies. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Cu(In,Ga)Se2 thin film solar cells from nanoparticle precursors

A non-vacuum process for Cu(In,Ga)Se₂ (CIGS) thin film solar cells from nanoparticle precursors was described in this work. CIGS nanoparticle precursors was prepared by a low temperature colloidal route by reacting the starting materials (CuI, InI₃, GaI₃ and Na₂Se) in organic solvents, by which fine CIGS nanoparticles of about 15 nm in diameter were obtained. The nanoparticle precursors were then deposited onto Mo/glass substrate by the doctor blade technique. After heat treating the CIGS/Mo/glass layers in Se gas atmosphere, a complete solar cell structure was fabricated by depositing the other layers including CdS buffer layer, ZnO window layer and Al electrodes by conventional methods. The resultant solar cell showed a conversion efficiency of 0.5%.     

21.2%‐efficient fineline‐printed PERC solar cell with 5 busbar front grid

We evaluate industrial‐type PERC solar cells applying a 5 busbar front grid and fineline‐printed Ag fingers. We obtain finger widths down to 46 µm when using a stencil with 40 µm opening for the finger print, whereas the busbar is printed in a separate printing step with a different Ag paste (dual print). This compares to finger widths of 62 µm to 66 µm when applying print‐on‐print. The 5 busbar front grid with the best dual print process reduces the shadowing loss of the front grid to 4.0% compared to 5.8% for a conventional 3 busbar front grid printed with print‐on‐print. The 1.8% reduction in shadowing loss results in equal parts from the reduced finger width with dual print as well as from a reduced total busbar width of the 5 busbar design. The resulting PERC solar cells with 5 busbars demonstrate independently confirmed conversion efficiencies of 21.2% compared to 20.6% efficiency of the 3 busbar PERC solar cell. The increased conversion efficiency is primarily due to an increased short‐circuit current resulting from the reduced shadowing loss. To our knowledge, 21.2% conversion efficiency is the highest value reported so far for industry typical silicon solar cells with printed metal front and rear contacts. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Plasmon enhanced CdS-quantum dot sensitized solar cell using ZnO nanorods array deposited with Ag nanoparticles as photoanode

CdS-quantum dot sensitized solar cell using ZnO nanorods (ZnO NRs) array deposited with Ag nanoparticles (Ag NPs) as photoanode was fabricated. Light absorption effect of Ag NPs on improvement of the cell performance was investigated. Performance improvement of metal nanoparticles (MNPs) was controlled by the structure design and architecture. Different decorations and densities of Ag NPs were utilized on the photoanode. Results showed that using 5% Ag NPs in the photoanode results in the increased efficiency, fill factor, and circuit current density from 0.28% to 0.60%, 0.22 to 0.29, and 2.18 mA/cm² to 3.25 mA/cm², respectively. Also, incident photon-to-current efficiencies (IPCE) results showed that cell performance improvement is related to enhanced absorption in the photoanode, which is because of the surface plasmonic resonance and light scattering of Ag NPs in the photoanode. Measurements of electrochemical impedance spectroscopy revealed that hole transfer kinetics increases with introduction of Ag NPs into photoanode. Also, it is shown that chemical capacitance increases with introduction of Ag NPs. Such increase can be attributed to the surface palsmonic resonance of Ag NPs which leads to absorption of more light in the photoanode and generation of more photoelectron in the photoanode.     

纳米硅(nc-Si:H )/晶体硅(c-Si)异质结太阳电池的数值模拟分析

运用美国宾州大学发展的AMPS程序模拟分析了n-型纳米硅（n+-nc-Si:H）/p-型晶体硅(p-c-Si)异质结太阳电池的光伏特性.分析表明，界面缺陷态是决定电池性能的关键因素，显著影响电池的开路电压（VOC）和填充因子（FF），而电池的光谱响应或短路电流密度（JSC）对缓冲层的厚度较为敏感.对不同能带补偿（bandgap offset）的情况所进行的模拟分析表明，随着ΔEc的增大，由于界面态所带来的开路电压和填充因子的减小逐渐被消除，当ΔEc达到05eV左右时界面态的影响几乎完全被掩盖.界面层的其他能带结构特征对器件性能的影响还有待进一步研究.最后计算得到了这种电池理想情况下（无界面态、有背面场、正背面反射率分别为0和1）的理论极限效率ηmax=3117% (AM15，100mW/cm2，040—110μm波段).     

Silver‐Based Nanoparticles for Surface Plasmon Resonance in Organic Optoelectronics

Organic optoelectronic devices including organic light‐emitting diodes (OLEDs) and polymer solar cells (PSCs) have many advantages, including low‐cost, mechanical flexibility, and amenability to large‐area fabrication based on printing techniques, and have therefore attracted attention as next‐generation flexible optoelectronic devices. Although almost 100% internal quantum efficiency of OLEDs has been achieved by using phosphorescent emitters and optimizing device structures, the external quantum efficiency (EQE) of OLEDs is still limited due to poor light extraction. Also, although intensive efforts to develop new conjugated polymers and device architectures have improved power conversion efficiency (PCE) up to 8%–9%, device efficiency must be improved to >10% for commercialization of PSCs. The surface plasmon resonance (SPR) effect of metal nanoparticles (NPs) can be an effective way to improve the extraction of light produced by decay of excitons in the emission layer and by absorption of incident light energy within the active layer. Silver (Ag) NPs are promising plasmonic materials due to a strong SPR peak and light‐scattering effect. In this review, different SPR properties of Ag NPs are introduced as a function of size, shape, and surrounding matrix, and review recent progress on application of the SPR effect of AgNPs to OLEDs and PSCs.     

Plasmonic DSSC performance of spray deposited Ag-ZnO and Au-ZnO films

Plasmonic silver-ZnO (Ag-ZnO) and gold-ZnO (Au-ZnO) thin films were deposited by simple and cost-effective spray pyrolysis technique (SPT). The compositional and optical properties of deposited films were investigated by XPS and UV-Vis spectroscopy, respectively. The surface plasmon resonance (SPR) related absorption peaks were observed in visible region.Also, the effect of metal addition on the photovoltaic performance was investigated. By utilizing Au–ZnO and Ag–ZnO films as photoanodes in dye-sensitized solar cells (DSSCs), the photovoltaic performance was improved. The photoconversion efficiencies of 0.93 % and 1.7 % were obtained for Ag–ZnO and Au-ZnO based DSSCs, respectively.