Ag纳米粒子等离子体共振增强太阳能电池吸收

针对薄膜太阳能电池硅薄膜层吸收效率较低的问题,提出了运用金属纳米粒子局域表面等离子体共振(LSPR)增强太阳能电池的吸收效率,采用时域有限差分(FDTD)法,模拟计算了太阳能电池中不同厚度的硅薄膜层吸收特性,分析了不同几何参数的矩形Ag纳米粒子与Ag背反射膜对增强太阳能电池吸收效率的影响作用。计算结果表明,硅薄膜层厚度为500nm的太阳能电池具有较高的吸收效率,通过调整Ag纳米粒子的相关参数,有效地降低了太阳电池硅薄膜表面的反射损耗,取得最大吸收增强因子为1.35。Ag背反射膜有效地降低了Ag纳米粒子硅薄膜结构的透射损耗,其最大的吸收增强因子达到1.42。     

WO3对Rubrene/C70有机太阳能电池性能的改善

研究了WO₃对Rubrene/C₇₀有机太阳能电池 (OSCs)性能的 改善,制备了结构为ITO/WO₃/Rubrene/C₇₀/BCP/Al的OSCs,其中WO₃插入在I TO和Rubrene中间作为阳极修饰层。通过优化WO₃的厚度,研究了WO₃对OSCs性能的改善及其作用机理。实验发现,器件的短路电流Jsc、开路电压V_oc、 填充因子(FF)、光电转换效率(PCE)和串联电阻Rs等性能参数随WO₃厚度的变化呈规律性变化;当 WO₃厚度小于80 nm时,器件PCE随着厚度的增加不断增大;当W O ₃厚大于80 nm时,器件PCE随着厚度的 增加不断减小;当WO₃厚度为80 nm 时,器件PCE达到最高为1.03%, 相应的J sc、V_oc、FF分别为2.81mA·cm－2、 0.83V、43.85%,Rs为45.3Ω·cm²,对比没有WO₃修饰层, 器件的J_sc、V_oc、FF和PCE分别提高了31%、137%、17%,Rs降低了33%。     

石墨烯掺杂Cs2CO3作为高效电子注入层的OLEDs性能研究

研制了石墨烯掺杂Cs₂CO₃(Cs₂CO₃:Graphe ne )作为高效电子注入层、结构为ITO/N,N′-bis-(1-naphthyl) -N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB)(50 nm)/tris-(8-hydroxy quinoline)-aluminum Alq₃(80 nm)/Cs₂CO₃:Gra phene (mss 20% 1nm)/Al(120 nm)的OLEDs。将其与标准器件ITO/NPB(50 nm)/Alq₃(80 n m)/LiF(0.5 nm)/Al(120 nm)作性能比较,研究石墨烯掺杂在Cs₂CO₃中作为电子注入层 对 OLEDs性能的影响。结果表明,基于Cs₂CO₃:Graphene结构作为电子注入层的器 件效率要高于LiF作为电子注入层的器件,其最大电流效率达到2.02 cd/A, 是标准器件的2.59倍;亮度也高于LiF作为电子注入层的器件,在10 V时达 到最大值7690cd/m²,是标准器件最大亮度 的2.07倍。性能得到提高的主要机理是由于Cs₂CO₃:Graphene的引入提高了电子注入效率。     

低温处理的TiO2纳米颗粒薄膜作为缓冲层的有机光伏电池

通过溶胶凝胶法(sol-gel)合成了TiO₂纳米颗 粒(NPs),制备了结构为 ITO/PEDOT:PSS/P3HT:PCBM/TiO₂/Al的有机太阳能电池(OSC)器件。通过优化阴极缓冲 层TiO₂NPs的 热处理温度,考察了温度以及溶剂对TiO₂NPs薄膜的光学性能、形貌结构和电学 性能的影响,并研究了其对OSC性能的影响及作用机理。实验发现,TiO₂NPs处理温度 为80℃时,器件 的效率达到了2.52%。相对于参比器件,器件的光电转换效率(PCE) 、填充因子(FF)分别提高了60%、64.7%。     

TiO2掺杂浓度对倒装白光数码管光色性能的影响

采用热压法将TiO₂按一定计量比掺入AB混合胶制备折射胶层,在芯片和荧光粉胶层 间利用甩胶旋 涂工艺添加折射胶层,封装成白光数码管;对样品的光色性能进行了测试和机 理分析。结 果表明,折射层中掺杂TiO₂颗粒浓度为0.3%时,白光数码管单笔段 光通量达到了最高值175 lm,比TiO₂浓度为0%时提高了约为7.5%。在相同测试条件下,掺杂0.3%浓度TiO₂颗粒的倒装白光数码管比传统点胶 白光数码管平均光通量提高了约为6.5%,平均色温下降约为 9.6%,出光一致性更理想。TiO₂颗粒的掺入不 仅提高了器件光通量,降低了色温,同时为白光数码管实现远程荧光粉涂覆工艺提供了一种 有效的途径。     

Ca3Y2(Si3O9)2:Tb3+绿色荧光粉的光谱特性

采用高温固相法制备了Ca₃Y₂(Si₃O₉)₂: Tb³⁺绿色荧光粉,研究了材料的光学性能。X 射线衍射(XRD)结果显示,掺杂少量的Tb³⁺,并未影响Ca₃Y₂(Si₃O₉)₂材料 的晶相结构。Ca₃Y₂(Si₃O₉)₂:Tb³⁺ 荧光粉的激发光谱由较强的4f^75d1宽带吸收(200～300 nm )和较弱的4f-4f电子跃迁吸收 (300～500 nm)构成,主激发峰位于236nm。取波长分别为236、376和482nm的光 作为激发源时,发现样品的主发射峰均位于544 nm,对应Tb³⁺的⁵D 4→⁷F₅跃迁发射。以236nm 紫外光作为激发源,监测544nm主发射峰,随Tb³⁺浓度 的增大,Ca₃Y₂(Si ₃O₉)₂:Tb³⁺的荧光寿命逐渐减小,但在实验范围内并未出现浓度猝灭现象。     

SiNx/SiOxNy叠层结构防潮能力的研究

研究了等离子体增强化学气相沉积(PECVD)工艺参数对SiN_x及SiO_xN_y防潮能力的影响,并测试了SiN_x/SiO_xN_y叠层薄膜的水汽渗透速率(WVTR)。实验结果表明:单层SiN_x薄膜和SiO_xN_y薄膜都存在临界厚度,当膜厚大于临界值时,继续增大厚度不会明显改善薄膜的WVTR。当沉积温度从50℃提高到250℃,SiN_x薄膜的WVTR从0.031g/(m²·day)降至0.010g/(m²·day)。SiO_xN_y沉积时,增大N₂O通入量对薄膜的WVTR影响不明显,但可以有效改善薄膜的弯曲性能。最后,4个SiN_x/SiO_xN_y叠层膜的WVTR下降到了4.4×10-4g/(m²·day)。叠层膜防潮能力的显著提升归因于叠层结构可以有效解耦层与层之间的缺陷,延长水汽渗透路径。     

TiO2基染料敏化太阳能电池的表面修饰及性能研究

采用水热法制备TiO₂浆料,用La(NO₃)₃溶 液浸泡TiO₂薄膜获得修饰电极。用X射线光电子能谱(XPS) 和扫描电子显微镜(SEM)对修饰电极的主要成分及形貌进行表征的结果显示,电极薄膜分为 上下两层,表 面包覆层粒径较大,为La₂O₃颗粒;下层颗粒粒径较小,为TiO₂颗粒。电流-电压测 试结果显示,与修饰 前相比,用La(NO₃)₃溶液浸泡30min获得的膜电极性能最优,使 开路电压和短路电流分别提高了6.8%和 18.5%。电化学阻抗谱(EIS)测试结果表明,相同偏压下,TiO₂/La ₂O₃电极界面复合电阻比TiO₂要大,说明 La₂O₃包覆层在一定程度上抑制了界面的电子复合,改善了电池的光电化学性能。     

稀土Er掺杂的MoSe2纳米线的制备及发光特性研究

本文研究了稀土掺杂硒化钼(MoSe₂)垂直纳米线 的制备及光学特性。以分析纯硒化钼 粉末为原料,采用热蒸发方法在Si衬底上沉积硒化钼垂直纳米线,并在其生长过程中利用硝 酸鉺进行原位掺杂。利用原子力显微镜(AFM)、X射线衍射仪(XRD)、紫外-可见分光光度计 和 荧光光谱仪研究了掺杂硒化钼薄膜的表面形貌﹑晶体结构﹑光吸收和特性。发现掺杂后MoSe ₂纳米线的结晶性更强,长度增加2倍以上。同时,掺杂后纳米线的可见光吸收和光致发光 强 度明显增强,760 nm处MoSe₂纳米线的带间跃迁的本征发射增强4倍 以上。另外,Er³⁺掺杂后 ,在590 nm和650 nm处增加了2个来自Er³⁺离子的发射,说明稀土掺杂后发光峰增加,使 光谱谱线更加丰富。以上结果表明,稀土掺杂可显著增强硒化钼的结晶性、光吸收和发光效 率,使其可用于制备超薄、高效率的太阳能电池、光探测器等光电子器件。     

在复合衬底γ-Al2O3/Si(001）上生长GaN

采用分子束外延（MBE）生长方法，使用γ-Al₂O₃材料作为新型过渡层，在Si(001）衬底上获得了没有裂纹的GaN外延层，实验结果表明使用γ-Al₂O₃过渡层有效地缓解了外延层中的应力. 通过生长并测试分析几种不同结构的外延材料，研究了复合衬底γ-Al₂O₃/Si (001）生长GaN情况，得到了六方相GaN单晶材料，实现了GaN c面生长. 预铺薄层Al及高温AlN层可以提高GaN晶体质量，低温AlN缓冲层可以改善GaN表面的粗糙度. 为解决Si(001）衬底上GaN的生长问题提供了有益的探索.     

Cathodic multilayer transparent electrodes for ITO-free inverted organic solar cells

We demonstrate cathodic multilayer transparent electrodes based on a ZnS/Ag/TiO_x (ZAT) structure for ITO-free inverted organic solar cells. A quality solution-based TiO_x layer is adopted as an inner dielectric layer to modify the effective work function of Ag, ensuring the ZAT electrode works as a cathode. The effect of the TiO_x layer is seen on the open-circuit voltage of a solar cell incorporating this layer, increasing to 900 mV from 600 mV in the case of a cell with a bare Ag layer for a bulk-heterojunction of poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl C₇₀-butyric acid methyl ester (PCBM70). The results of a joint theoretical and experimental study indicate that the photocurrent of a ZAT-based solar cell can be significantly enhanced by carefully balancing the optical-spacer and cavity-resonance effects, both of which are modulated by the thickness of the WO₃ layer used as a hole-collection layer at the top anode side. ZAT-based inverted solar cells with an optimized structure exhibit a power conversion efficiency as high as 5.1%, which is comparable to that of the ITO-based equivalent.     

原子层沉积氧化铝薄膜对多晶太阳能电池表面钝化的影响

A stack of Al2O3/SiNx dual layer was applied for the back side surface passivation of p-type multi-crystalline silicon solar cells, with laser-opened line metal contacts, forming a local aluminum back surface field （local Al-BSF） structure. A slight amount of Al2O3, wrapping around to the front side of the wafer during the thermal atomic layer deposition process, was found to have a negative influence on cell performance. The different process flow was found to lead to a different cell performance, because of the Al2O3 wrapping around the front surface. The best cell performance, with an absolute efficiency gain of about 0.6% compared with the normal full Al-BSF structure solar cell, was achieved when the Al2O3 layer was deposited after the front surface of the wafer had been covered by a SiNx layer. We discuss the possible reasons for this phenomenon, and propose three explanations as the Ag paste, being hindered from firing through the front passivation layer, degraded the SiNx passivation effect and the Al2O3 induced an inversion effect on the front surface. Characterization methods like internal quantum efficiency and contact resistance scanning were used to assist our understanding of the underlying mechanisms.     

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.     

Nanostructure effect of V2O5 buffer layer on performance of polymer-fullerene devices

Nanostructure of solar cell materials is often essential for the device performance. V₂O₅ nanobelt structure is synthesized with a solution process and further used as an anode buffer layer in polymer solar cells, resulting insignificantly improved power conversion efficiency (PCE of 2.71%) much higher than that of devices without the buffer layer (PCE of 0.14%) or with V₂O₅ powder as the buffer layer (1.08%). X-ray diffraction (XRD) results indicate that the V₂O₅ nanobelt structure has better phase separation while providing higher surface area for the P3HT:PCBM active layer to enhance photocurrent. The measured impedance spectrums show that the V₂O₅ nanobelt structure has faster charge transport than the powder material. This work clearly demonstrates that V₂O₅ nanobelt has great potential as a substitute of the conventionally used PEDOT-PSS buffer layer for high performance devices.     

Zn1?xMgxO用于 CIGS 太阳电池的研究进展

Zn1-xMgxO透过率高、带隙可调,且与CIGS太阳电池在晶格和能带结构上匹配良好,可用作CIGS太阳电池缓冲层、窗口层,因此制备高质量的Zn1-xMgxO薄膜是提高太阳电池性能的关键。文章介绍了Zn1-xMgxO薄膜的结构特性、光学特性及制备方法;从Mg含量、Zn1-xMgxO膜厚及Zn1-xMgxO/CIGS界面处缺陷密度等方面概述了Zn1-xMgxO用于CIGS太阳电池的研究进展,并比较了Zn1-xMgxO与In2S3,ZnS,CdS等其他材料作缓冲层的CIGS太阳电池性能的差别。     

Optimized ITO-free tri-layer electrode for organic solar cells

The optical properties of ZnO/Ag/ZnO (ZAZ) multilayer structures were numerically modeled and calculated by a FDTD method. Such tri-layers were also manufactured using an ion beam sputtering plant. A good agreement is obtained between modelizations and realizations. The impact of the oxide thicknesses on the optical properties of the ZAZ structures were experimentally and numerically investigated, and allow us to adjust the spectral position of the transmission maximum. The transmission of these structures is optimized up to around 74%, on the whole absorption spectral range of the photoactive P3HT:PCBM bulk heterojunction. The best electrode design is glass/ZnO (30 nm)/Ag (14 nm)/ZnO (30 nm), which presents a sheet resistance of 7 Ω/□. The optimized ZAZ structure was successfully integrated in an organic solar cell as anode. A photovoltaic efficiency of 2.58% is obtained and is compared to an organic solar cell integrating a traditional ITO anode with an efficiency of 2.99%. Numerical calculations of the intrinsic absorption inside each layer of the organic solar cells are performed. Alternative ITO-free electrodes for organic solar cells are demonstrated.     

Enhancing conversion efficiency of inverted organic solar cells using Ag nanoparticles and long wavelength absorbing tin (II) phthalocyanine

Wide wavelength inverted organic solar cells (IOSCs) were fabricated and characterized by doping the active layer with long wavelength absorbing tin (II) phthalocyanine (SnPc). The hole-transporting layer (HTL) comprised Ag nanoparticles (NPs)-embedded poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). The short-circuit current density (J_sc) and power conversion efficiency (PCE) were considerably enhanced. It is attributed to that Ag NPs result in the enhancement of the scattering and reflection of light, leading to increase absorption efficiency in the active layer of IOSCs. Moreover, the SnPc-doped active layer exhibits a long wavelength absorption and prevents the active layer from degradation by PCBM clusters. The optimized IOSCs exhibited an open circuit voltage (V_oc), J_sc, fill factor (F.F.), and PCE of 0.5 V, 10.34 mA/cm², 45.33% and 2.33%, respectively, under simulated AM1.5G illumination at 100 mW/cm².     

Broadband scattering of the solar spectrum by spherical metal nanoparticles

Metal nanoparticles offer the possibility of improved light trapping in solar cells, but careful design is required to maximise scattering and minimise parasitic absorption across the wavelength range of interest. We present an analysis of the broadband scattering and absorption characteristics of spherical metal nanoparticles, optimized for either crystalline silicon (c‐Si) or amorphous silicon (a‐Si:H) solar cells. A random two‐dimensional array of optimally sized Ag spheres can scatter over 97% of the AM1.5 spectrum from 400 to 1100 nm. Larger particles are required for c‐Si devices than a‐Si:H due to the increased spectral range, with optimum particle sizes ranging from 60 nm for a‐Si:H to 116 nm for c‐Si. Positioning the particles at the rear of the solar cell decreases absorption losses because these principally occur at short wavelengths. Increasing the refractive index of the surrounding medium beyond the optimum value, which is 1.0 for a‐Si:H and 1.6 for c‐Si, shifts absorption to longer wavelengths and decreases scattering at short wavelengths. Ag nanoparticles scatter more of the solar spectrum than Au, Cu or Al nanoparticles. Of these other metals, Al can only be considered for a‐Si:H applications due to high absorption in the near‐infrared, whereas Au and Cu can only be considered for the rear of c‐Si devices due to high absorption in the ultraviolet (UV) and visible. In general, we demonstrate the importance of considering the broadband optical properties of metal nanoparticles for photovoltaic applications. Copyright © 2012 John Wiley & Sons, Ltd.     

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.