Organic solar cells with very high fill factor and voltage using tetrapropyl‐tetraphenyl‐diindenoperylene as green donor

We present 2,3,10,11‐tetrapropyl‐1,4,9,12‐tetraphenyl‐diindeno[1,2,3‐cd:1′,2′,3′‐lm]perylene (P4‐Ph4‐DIP) as new green donor for small molecule organic solar cells (SMOSC). P4‐Ph4‐DIP absorbs in the green spectral range of 490–580 nm and thus is a decisive building block towards broad coverage of the sun spectrum. SMOSC with P4‐Ph4‐DIP as donor and C₆₀ as blue‐absorbing acceptor display very high fill factors FF > 76% and open circuit voltages of 0.99 V, reaching η = 1.92% for 12 nm P4‐Ph4‐DIP. Current voltage and external quantum efficiency spectra suggest that an exciton diffusion length E_D < 20 nm is the main limiting factor. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Morphology controlled open circuit voltage in polymer solar cells

We report a strong dependence of open circuit voltage on the altered morphology of block copolymer (P3HT‐b ‐PPerAcr) based solar cells. The open circuit voltage increases dramatically by about 300 mV by increasing the amount of acceptor homopolymer within the block copolymer/homopolymer blends. The change in open circuit voltage is found to be in correlation with the enrichment of acceptor moiety at the film surface as identified by Atomic force microscopy (AFM) and X‐ray photoelectron spectroscopy (XPS). Based on this fact, an additional increase in open circuit voltage to its maximum values is achieved by introducing an acceptor buffer layer at the cathode interface. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

True nature of active layers in organic solar cells fabricated by sequential casting of donor and acceptor layers

The operation characteristics of nominal bilayer (BL) organic solar cells (OSCs), the active layers (ALs) of which consisted of sequentially casted bottom P3HT donor and top ICBA acceptor layers, resembled those of OSCs with bulk heterojunction (BHJ) ALs. Optical analysis and device simulations showed that such resemblance can be attributed to a similarity in the micromorphology of ALs; as‐deposited BL‐type ALs transformed spontaneously into BHJ‐type ALs. The inclusion of P3HT nanowires (NWs) in the donor layers resulted in different AL micromorphology and consequently a larger power conversion efficiency. Separate assessment of the exciton generation and charge–carrier transport and/or extraction showed that the contribution of P3HT NWs was more prominent in optical effects.

     

Influence of fullerene derivative replacement with TiO2 nanoparticles in organic bulk heterojunction solar cells

In an effort to develop hybrid organic solar cells with improved power conversion efficiency (PCE), devices based on poly (3-hexylthiophene) (P3HT):phenyl C₆₁-butyric acid methyl ester (PCBM) active layer and poly (3,4-ethylenedioxythiophene) (PEDOT):poly (styrenesulfonate) (PSS) buffer layers were prepared. A systematic replacement of PCBM was achieved by introducing nanostructured TiO₂ (∼15 nm particle size), dissolved separately in chlorobenzene (CB) and 1,2 –dichlorobenzene (DCB), to the (P3HT:PCBM) active layer while keeping a fixed amount for P3HT. To understand the effect of fullerene replacement with the inorganic metal oxide nanoparticles on different properties of resulting devices, a variety of techniques such as Current–Voltage (J–V) characteristics, Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM), Ultravoilet-Visible (UV–Vis) Spectrophotometry and External Quantum Efficiency (EQE) were employed. The addition of TiO₂ nanoparticles in the active layer improved the power conversion efficiency (PCE) of P3HT:PCBM devices. The addition of TiO₂ nanoparticles using CB as solvent enhanced the absorption in visible region and also introduced a red shift in the absorption spectra. A significant increase in EQE was observed for devices with TiO₂ nanoparticles in the active layer. Mixing TiO₂ also increased the surface roughness of the active layer where TiO₂ nanoparticles were found to agglomerate as their concentration increased relative to fullerene derivative. A complete agglomeration of TiO₂ was observed in the absence of PCBM.     

Investigating the performance of P3HT:PCBM organic solar cells involving gamma-irradiated PEDOT:PSS layer

In this work, we investigated for the first time the characteristics of (poly (3-hexylthiopene) and [6, 6]-phenyl C61-butyric acid methyl ester) (P3HT:PCBM) blends-based organic solar cell with 1.25?mg/mL boric-acid (H₃BO₃)-doped poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) layer which is irradiated under the 40 Gray (Gy) dose of gamma (γ) ray. Experimental results showed that the parameters of solar cell improved with exposure to low-dose gamma radiation. In particular, it has provided a significant improvement in short-circuit current density (J_sc) and power conversion efficiency (PCE). About 49% increase in PCE to 1.22% and 40% increase in J_sc to 6.28?mA/cm² was obtained between the bare device and the device containing irradiated PEDOT:PSS:H₃BO₃. Also, it was determined that the H₃BO₃-doped PEDOT:PSS is more stable to temperature. More importantly, solar cell containing gamma-irradiated PEDOT:PSS:H₃BO₃ showed best performance comparing to conventional PEDOT:PSS-based cell.     

采用高传导率银铜镍网格电极的柔性聚合物太阳能电池

采用一种新的阳极材料:银、铜、镍的复合金属网格阳极,利用旋涂法制成了活性层为P3HT (poly(3-hexylthiophene)):PCBM([6,6]-phenylC61-butyricacidmethylester)的柔性衬底聚合物太阳能电池.制备了5种不同结构的柔性聚合物太阳能电池器件,将采用新型阳极材料的柔性衬底聚合物太阳能电池与传统ITO(Indium tin oxide)阳极的柔性衬底聚合物太阳能电池进行对比,发现新型阳极材料所制成的器件性能得到大幅度的提高,其电池器件在50 mW/cm~2强度光照下,开路电压(V_(oc))为0.54 V,短路电流密度(J_(sc))为5.39 mA/cm~2,能量转换效率为2.060%.     

CH3NH3PbI3/poly‐3‐hexylthiophen perovskite mesoscopic solar cells: Performance enhancement by Li‐assisted hole conduction

To address if the non‐triphenylamine derivative hole transporting materials such as P3HT (poly‐3‐hexylthiophene) could also exhibit high device efficiency in mesoscopic MAPbI₃ perovskite solar cells, we examined the effect of Li‐TFSI (Li‐bis(trifluoromethanesulfonyl) imide) and t‐BP (4‐tert‐butylpyridine) additives added in P3HT on device performance. Unlike the triphenylamine HTMs, the P3HT thiophene HTM without amine moiety was not doped by the additives but its conductivity was significantly improved by the Li‐TFSI/t‐BP mediated additional hole conduction. By inclusion of Li‐TFSI/t‐BP additive, we could fabricate more efficient mesoscopic MAPbI₃ perovskite solar cells with smaller hysteresis with respect to scan direction due to Li mediated additional hole conduction. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Photoconductivity as loss mechanism in organic solar cells

We observe that the reverse current under illumination in solar cells containing C₆₀ and ZnPc is dominated by a photoshunt. This shunt, not present in the dark, causes a linear current–voltage relation under illumination showing no saturation. Although observable in bulk heterojunctions, this effect is more pronounced in the presence of a pristine C₆₀ layer. An internal quantum efficiency larger than unity under an applied negative voltage and in the spectral range where C₆₀ absorbs identifies charges which are injected in addition to those photogenerated. The photoshunt is also present in the power‐generating region and represents a loss mechanism limiting the fill factor in particular for flat heterojunction devices. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

石墨烯衍生物作为有机太阳能电池界面材料的研究进展

本文综述了石墨烯及其衍生物作为界面材料在有机太阳能电池中的应用, 包括作为阳极界面层、阴极界面层和叠层电池中间层等方面. 氧化石墨烯由于较好的透光性, 易于分散在水溶液中与溶液加工等优点已被应用在有机太阳能电池中. 对氧化石墨烯作为阳极界面层的研究包括通过部分还原或掺杂提高其导电性、通过引入高负电性原子提高其表面功函数, 以及通过与其他材料复合提高性能等. 同时, 本文综述了石墨烯衍生物及复合材料作为有机太阳能电池阴极界面层和叠层电池中间层的研究. 最后本文展望了石墨烯及其衍生物在有机太阳能电池与有机无机复合钙钛矿太阳能电池中的应用前景.     

The effect of annealing treatment on the performance of bulk heterojunction solar cells with donor and acceptor different weight ratios

Bulk heterojunction organic solar cells(OSCs) based on the blend of poly(2-methoxy-5(2'-ethyl-hexyloxy)-1,4-phenylenevinylene(MEH-PPV) and [6,6]-phenyl C61 butyric acid methyl ester(PCBM) with different weight ratios(from 1:3 to 1:5) have been fabricated and the effect of annealing treatment on the performance of OSCs has also been studied.Experimental results point to the best optimized doping concentration 1:4 for MEH-PPV:PCBM.Furthermore,it is found that the devices with annealing treatment at 150℃ with ...     

Bulk heterojunction organic photovoltaic cell fabricated by the electrospray deposition method using mixed organic solvent

A high‐efficiency bulk heterojunction organic photovoltaic cell (OPV) was achieved by the electrospray deposition method. The surface roughness of the P3HT:PCBM thin film can be reduced using the mixed solvent consisting of o‐dichlorobenzene (o‐DCB) and acetone. The effect of acetone concentration is related to its dielectric constant. Under an optimized concentration of acetone in o‐DCB (20 vol%), the P3HT/PCBM active layer with a smooth surface can be formed, and the power conversion efficiency of the OPV was 1.9%.

     

NiO_x作为空穴传输层对有机太阳能电池光吸收的影响

基于多层膜系模型的传输矩阵方法、麦克斯韦方程和光子吸收方程,研究了NiOx作为替代3,4-乙撑二氧噻吩:聚苯乙烯磺酸盐(PEDOT:PSS)的空穴传输材料对聚3-己噻吩(P3HT)和富勒烯衍生物([6,6]-phenyl-C61-butyric acid methyl ester,PC61BM)共混体异质结有机太阳能电池器件内部光电场分布和光吸收特性的影响.分别制备了以NiOx和PEDOT:PSS为空穴传输层,P3HT:PCBM为活性层的有机太阳能电池,并通过数值模拟的方法比较了NiOx和PEDOT:PSS两种空穴传输材料对器件光伏特性的影响.结果表明:10 nm的NiOx空穴传输层器件比40 nm的PEDOT:PSS器件获得了更大的短路电流和填充因子,并具有更高的能量转化效率.     

PTCBI作为阴极修饰层对Rubrene/C70器件性能的影响

制备了结构为ITO/MoO₃(6 nm)/Rubrene (30 nm)/C₇₀ (30 nm)/PTCBI(x nm)/Al (150 nm)器件, 研究了四羧基苝的衍生物PTCBI作为阴极修饰层对Rubrene/C₇₀有机太阳能电池的作用. 实验结果显示, 在C₇₀与Al电极之间插入PTCBI 后, 电池性能得到明显改善; 分析表明, 插入PTCBI后, 活性层与阴极形成了良好的欧姆接触, 提高了器件的内建电场, 同时PTCBI避免了激子与Al电极的接触, 减少了在制备过程中高动能Al对C₇₀的破坏. 进一步考察了PTCBI厚度对电池的性能的影响, 结果显示, 厚度为6 nm的PTCBI 层器件性能最佳, 其开路电压(V_OC)、填充因子(FF)、短路电流密度(J_SC)与功率转换效率(ηP)与未插入PTCBI修饰层的器件相比分别提高了70.4%, 55.5%, 125.1%, 292.2%. 当PTCBI的厚度大于6 nm时, 激子解离后产生的自由电子会在PTCBI与阴极界面积累, 导致器件J-V曲线出现S形.     

胆甾液晶掺杂活性层对有机太阳能电池性能的影响

以poly(3-hexylthiophene)(P3HT)为电子给体,indene-C60bisadduct(ICBA)为电子受体,通过掺杂不同浓度胆甾液晶氯化胆甾醇制备了有机体异质结太阳能电池.结果表明,适当浓度掺杂使器件的开路电压提高到了0.78 V,但短路电流密度却有所降低,填充因子几乎不变,能量转换效率提高了10%.利用X射线、光致发光、原子力显微镜及紫外-可见吸收光谱进行表征,发现液晶掺杂对活性层的结晶度、分子内部排列情况、薄膜表面形貌和光吸收特性等都有明显影响.     

质子辐射损伤对单结GaAs/Ge太阳电池暗特性参数的影响

基于p-n结暗特性双指数模型,对经质子辐射后的单结GaAs/Ge太阳电池的暗特性I-V曲线进行数值拟合,确定了单结GaAs/Ge太阳电池在辐射前后的四个暗特性特征参数,即串联电阻R_s、并联电阻R_(sh)、扩散电流I_(s1)和复合电流I_(s2).研究结果表明,质子辐射后单结GaAs/Ge太阳电池的R_s,R_(sh),I_(s1)和I_(s2)四个暗特性参数均发生显著变化.经低能质子辐射后,单结GaAs/Ge太阳电池的R_(sh)随位移损伤剂量的增加而减小,而R_s,I_(s1)和I_(s2)三个参数随位移损伤剂量的增加而增大,其中串联电阻随位移损伤剂量线性增加而与辐射质子能量无关.理论分析表明,上述参数的变化与质子辐射损伤区域分布有关.基区和发射区的损伤主要引起单结电池串联电阻和扩散电流的增加;结区的损伤导致并联电阻减小,复合电流增大.     

Influence of optical interference and carrier lifetime on the short circuit current density of organic bulk heterojunction solar cells

Based on simple analytical equations, short circuit current density (J_SC) of the organic bulk heterojunction solar cells has been calculated. It is found that the optical interference effect plays a very important role in the determination of J_SC; and obvious oscillatory behaviour of J_SC was observed as a function of thickness. At the same time, the influence of the carrier lifetime on J_SC also cannot be neglected. When the carrier lifetime is relatively short, J_SC only increases at the initial stage and then decreases rapidly with the increase of active layer thickness. However, for a relatively long carrier lifetime, the exciton dissociation probability must be considered, and J_SC behaves wave-like with the increase of active layer thickness. The validity of this model is confirmed by the experimental results.     

有机共混结构叠层太阳电池的研究进展

有机太阳电池由于质轻、价廉、柔性,受到人们的广泛关注.单个有机材料只能吸收部分太阳光,叠层结构的太阳电池将不同吸收带隙的有机材料通过中间层连接起来,既能充分吸收太阳光,又能提高太阳电池的开路电压或短路电流.本文综述了近年来有机共混结构叠层太阳电池的研究进展,介绍了各种叠层有机太阳电池的结构、原理及性能,阐述了国内外有机叠层太阳电池研究的现状及存在问题,为高性能有机太阳电池的研究提供有价值的参考.     

阴极功函数和激子产生率对肖特基接触单层有机太阳能电池开路电压的影响研究

运用数值方法系统研究了阴极功函数,激子产生率和温度对肖特基接触单层有机太阳能电池开路电压的影响,分析了开路电压条件下有机太阳能电池有机层内载流子和电场的分布.结果表明在阳极功函数一定时开路电压随着阴极功函数（W_c）的降低而增大,当W_c接近有机材料的最低未被占据分子轨道（LUMO）能级时开路电压不再增大而达到一个饱和值,饱和开路电压随激子产生率的提高而增大;对于给定的阳极和阴极功函数,开路电压随激子产生率的提高而增大并在激子产生率达到一 关键词： 开路电压 温度 阴极功函数 单层有机太阳能电池     

给体-受体型有机太阳电池光敏层的优化设计

针对有机给体-受体型异质结薄膜太阳电池，基于薄膜中的光学干涉效应和激子扩散理论建立模型，定量分析了有机层厚度对太阳电池性能的影响，通过限制有机光敏层厚度来控制由光学干涉效应引起的局部光子密度(光强度)的分布，进而优化有机层的吸收效率和激子扩散效率，以此达到提高器件光伏效率的目的.并通过实验进行了验证. 关键词： 有机太阳电池 给体-受体 优化设计 激子