• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Research Progress in Surface Passivation of Colloidal Quantum Dots Solar Cells

    2020-10-13 06:26:14
    陶瓷學(xué)報 2020年1期

    (Jingdezhen Ceramic Institute, Jingdezhen 333403, Jiangxi, China)

    Abstract: As one of the third-generation solar cells, colloidal quantum dot solar cells have attracted huge attentions owing to their simple preparation process and device flexibility. Notably, the surface passivation of the colloidal quantum dots for building the active layer has a critical impact on the device performances. This paper was aimed to briefly describe the recent research progress in surface passivation of the device-graded colloidal quantum dots and the effects of various ligands on device performances, with prospects of the future development trend.

    Key words: colloidal quantum dots; ligand exchange; passivation; perovskite

    1 Introduction

    As a group of nanomaterials, colloidal quantum dots (CQDs) include II-VI and II-V compounds, with particle sizes in the range of 1-10 nm. Due to their small sizes, CQDs have various unique physic and chemical properties, such as size effect, surface effect, quantum tunneling effect and dielectric confinement effect[1-4]. Because their bandgap,electron state energy level and surface chemistry can be adjusted over a wide range, with the presence of multi-exciton generation (MEG) effect, CQDs have been used as active layers (light absorption layers) of solar cells[5].

    Because of the relatively large specific surface area, the surface of CQDs usually contains numerous dangling bonds, which easily trigger the “selfquenching” of the photogenerated carriers. Also, the transport of carriers in between the CQDs possibly induces trapping effect. The carriers could even be captured by the barren defects as the recombination-centers. All these effects could be dynamically competitive with the radiation recombination, so that the latter will be weakened,thus resulting in reduced luminescent efficiency of the CQDs films[6,7]. To prevent the occurrence of self-quenching, CQDs are passivated by using surface ligands, so as to reduce the density of defects at the surface. Generally, the effects of surface ligands on physical and chemical properties of CQDs include (i) influencing their nucleation and growth in the synthesis process, (ii) offering static stability to the CQDs, (iii) altering photoelectric properties of the CQDs through the modification of energy level and carrier mobility and (iv) minimizing the negative effect of environment[7-11].

    Because long-chain macromolecules have special groups at the ends, they serve to control the reactivity of the precursors of CQDs. As a result, the nucleation and crystal growth of CQDs can be controlled to take place at different stages, so that the CQDs will have desired crystal size, size distribution and morphology. To this end, long-chain macromolecules, such as oleic acid and oleylamines,are used for the synthesis of CQDs[12]. However,due to their insulating characteristics, these macromolecules could limit the electrical performances when CQDs are used to fabricate photoelectronic devices, such as photodetectors and solar cells. In this case, it is necessary to use other ligands to passivate the surface of CQDs. This article is aimed to overview the progress in the effect of ligands on CQDs-based photovoltaic devices, by focusing on surface ligand exchange and passivation.

    2 Ligand Exchange

    To develop high performance devices, the macromolecules at the surface of CQDs should be replaced by ligands with short-chain molecules or atomic scale items. Currently, there are two types of exchange methods, i.e., solid-state ligand exchange(SSLE) and liquid phase transfer exchange (LPTE),both of which have advantages and disadvantages.

    In SSLE process, CQDs are dispersed in nonpolar solvents (such as toluene, hexane or octane)with concentrations of 30-80 mg/ml, which were then coated on transparent substrates as thin layers.The CQDs layers were treated with short-chain molecules or atomic level ligands, in order to induce exchange reaction. After that, the samples are cleaned with methanol or acetonitrile to remove the residual ligands[13-16]. To develop high performance of photoelectronic devices, this process can be repeated multiple times to make the CQDs layers reach the desired thickness. In this regard,layer-by-layer (LBL) method has been widely employed to deposit CQDs layers. With the combination of LBL and SSLE, the inter-particle distance of CQDs can be readily controlled, while the CQDs films usually have high quality surface,which are beneficial to improving the carrier mobility. However, the multiple steps of deposition of CQDs, SSLE and cleaning result in low utilization efficiency of the CQDS, high consumption of solvents and long time requirement, as shown schematically in Fig. 1 (a).

    In comparison, in LPTE, CQDs particles are wrapped with nonpolar long-chain alkyl molecules that are already dispersed in the solvents, which are mixed with ligands that are dissolved in polar solvents, so as to trigger the desired exchange,followed spin-coated into a film in one step. LPTE method has high utilization efficiencies for the precursors and solvents, but the thick CQDs film tend to crack due to the large lateral stress, as illustrated in Fig. 1 (b).

    Currently, CQDs active layers are usually fabricated by using the two strategies. SSLE process is simple and cost-effective, but the proton solvent(e.g., methanol) often leads to loss of the ligand and induces defects in the films[18]. LPTE has no such problems, while the key requirement is that interaction between the long-chain molecules and the CQDs should be sufficiently weak and nonoxidative polar solvents should be used for the exchange reactions[19]. Therefore, in practice, a trade-off must be considered in selecting reasonable exchange processes.

    Fig.1 (a) Schematic diagram of solid state ligand exchange and film fabrication, (b) Schematic diagram of liquid phase transfer exchange and film fabrication, taking MPA as an example [16]

    3 Passivation with Organic Ligands

    When the functional and specific groups of the organic ligands are anchored onto the surface of the CQDs, their interaction with environment can be adjusted and they will be stabilized in the solutions.It has been found that the carrier mobility of the CQDs films is exponentially increased with decreasing length of the ligand molecules. Therefore, it is desired to use short-chain ligands to replace the long-chain molecules in the CQDs films. The commonly used short-chain organic ligands include Aromatic mercaptans[20,21], mercapto carboxylic acids[22],alkylamines[23]and organometallic ligands[24].

    Due to the strong interaction with surface cations of CQDs, thiol groups are usually adopted for the exchange reactions. For instance, Chuang et al[25]used 1, 2-ethanedithiol (EDT) as the ligand to treat PbS CQDs, which served as electron barrier layer. The resultant solar cells exhibited a power conversion efficiency (PCE) of 8.55%, which was much higher than that of the PbS-based device without passivation. Owing to the encapsulation effect of EDT, the solar cells showed no change in performance for 150 days. The exchange process is schematically demonstrated in Fig.2.

    Kitada et al[26]employed ethylenediamine to exchange with oleic acid encapsulated CQDs,confirming that the short-chain exchange could shorten the inter-particle distance of the CQDs. As a result, the carrier mobility was significantly improved, thus leading enhancement in the efficiency of solar cells, further proving the determining effect of the chain length of the ligand molecules on the electrical performances of the CQDs-based devices.

    Fig.2 Schematic diagram of thiol ligand exchange

    Ming et al[27]studied the effect of chain length of ligands on the exchange reaction for AgBiS2CQDs. It is observed that the chain property of the ligand had a straightforward effect on energy level of the CQDs, thus influencing the electrical performance of the photoelectronic devices. Brown et al[28]adopted different ligands to modify the surface of CQDs, whereas the results further confirmed the effect of chain length of the ligands by using UPS to measure the variation in the energy level of the CQDs after exchange with different ligands. According to energy level matching principle[28-30], the output of a photovoltaic device can be controlled by adjusting the energy levels of the different layers, which can be used as reference for the design of high performance photoelectronic devices.

    4 Passivation with Inorganic Ligands

    In 2009, Kovalenko et al[31]for the first time proposed to use inorganic ligands for the exchange reactions of CQDs. Since then, various inorganic ligands have been reported, such as metal chalcogenide complexes (MCCs) and metal halides.The use of inorganic ligands not only improved the stability of the CQDs and passivated their surface defects, but also enhanced the coupling of electron wave functions and promoted the carrier transportation[32].

    Fig.3 Liquid phase ligand exchange process between metal halide precursor and ammonium acetate(process 1: ligand exchange, process 2: CQDs precipitation) [34]

    4.1 Metal chalcogenides

    According to the hard-soft acid-base (HSAB)theory, Kovalenko et al[31]developed a dual-phase liquid ligand exchange reaction to prepare MCCs-modified CQDs in polar organic system.Generally, the exchange occurs between the acid-base couple with comparable hardness metrics.The sulfur aions in chalcogenides (e.g., Na4SnS6and Na3AsS3) tend to react with the cations at the surface of CQDs, thus replacing the long-chain molecules.With the realization of exchange with MCCs, the inter-particle interactions of the CQDs are enhanced,thus leading to high carrier mobility. Although the report on this kind of ligands in the applications of photoelectronic devices (especially solar cells) is still not very popular, it is highly expected they will have great potential for such applications.

    4.2 Metal halides

    Currently, PbS is the most widely candidate for highly efficient CQDs-based heterojunction solar cells. As atomic scale ligands, metal halides can be used to replace the long-chain molecules to improve the carrier transport efficiency of PbS CQDs. The strong interaction between the halides and the cations at the surface of the CQDs helps to guarantee the perfect surface passivation. As a consequence,the carrier mobility is increased, while the concentration of defects in the CQDs films is decreased.

    In 2016, Liu et al[34]reported an exchange process with metal halides. With the aid of weak acidic ammonia ions, the oleic acid molecules of PbS CQDs can be completely replaced by [PbX3]-. After the exchange process, toluene was introduced into the N, N-dimethylformamide (DMF) to crush out the CQDs from the solvent system, which can help to remove the ammonia acetate and excessive lead halide, as shown schematically in Fig. 3. The as-obtained product was then re-dispersed in N-butylamine to prepare the spin-ink. PbS QCDs films spin-coated with the ink had a smooth surface and soft texture, resulting solar cells with a high PCE of 11.28%.

    In one word, the inter-particle distance of the CQDs films can be effectively shortened after the exchange reactions with metal chalcogenides and halides, thus leading an enhancement in carrier mobility. In addition, the CQDs after exchange with MCCs or metal halides should be dispersed in polar solvent with relatively high dielectric constant, e.g.,DMF. This is because the CQDs passivated with the smaller ligands require strong ions shielding effect conditions to form diffusion double layers, so that they can be well dispersed through electrostatic interactions[19,35], as schematically shown in Fig. 4.

    Fig.4 Schematic diagram of ligand exchange process(taking NH4I ligand as an example) [36]

    5 Passivation with Hybrid Ligands

    Hybrid ligands, consisting of both organic and inorganic ligands, have combined advantages of the two components[16,36]. In 2012, Alexander et al[37]proposed such an organic-inorganic hybrid passivation strategy. They mixed oleic acid encapsulated PbS CQDs and halide solutions at a relatively low temperature. After the exchange reaction, the passivated CQDs were dispersed in octane, followed by SSLE process with mercaptopropionic acid (MPA) in methanol. Finally,the passivated CQDs were made into solar cells,achieving a record PCE of 7.0%, which was much higher than those of the devices from the CQDs passivated with only organic[38]or inorganic[39]ligands, as illustrated in Table 1.

    Tab.1 Performances of different ligand passivated devices [37]

    Distance between oleic-acid-capped CQDs measured by GISAXS was 4.4 nm. In the SSLE process, after passivation with MPA, the average inter-particle distance of the CQDs films was reduced to 3.4 nm, while it was kept unchanged after the exchange with the inorganic ligand. As compared with the passivation with only inorganic ligand, the CQDs films were further densified after exchange with MPA due to its dual-functional groups. From the steric effect point of view, it is more difficult for organic ligands to passivate the CQDs due to their large molecules. In comparison, inorganic ligands have much smaller molecules, so that they can easily approach the locations with smaller spaces.Therefore, hybrid ligands would ensure that film densification and CQDs surface passivation are simultaneously maximized, as shown schematically in Fig. 5.

    Fig.5 Schematic cross-section of organic passivation (left)and mixed passivation (right) for PbS CQDs [37]

    The lower content of defects at the surface of the CQDs, the higher the voltage and PCE performances that can be achieved. In this aspect,hybrid ligand passivation has been proved to be an effective way to improve the voltage and PCE properties of CQDs based solar cells. The combination of inorganic ligand and MPA led to CQDs films with shorter inter-particle distance,higher film density, higher carrier mobility and thus higher PCE.

    6 Passivation with Perovskite Ligands

    Because of their large carrier diffusion length,adjustable bandgaps, high light absorption coefficient and high defect tolerance, perovskites have been widely used to passivate the surfaces of CQDs[40-46]. Perovskite passivation can be applied in two way, i.e., mixing and epitaxial method. In the first process, perovskite nanocrystals are well-mixed with the oleic acid-capped CQDs treated by chlorines in the same solvent system to trigger the halide ion exchange reaction. After that, an excess amount of ethanol is added to dissolve the excessive perovskite nanocrystals. The passivated CQDs were collected through centrifugation and dispersed in nonpolar solvent (e.g., hexane) for device fabrication[47].For the second process, perovskite precursor solutions in polar solvents are mixed with CQDs suspensions in nonpolar solvents. As a result,perovskite phase is epitaxially grown the surface of the CQDs, thus realizing surface passivation. The passivated CQDs are collected and dispersed in butylamine for film deposition[48].

    6.1 Mixed perovskite

    Considering the high migration rate of the halide ions in the halide-based perovskite nanocrystals, Zhang et al[47]proposed a new passivation technique, according to the HSAB and DFT theories. They studied the halide ion exchange reaction between CsPbX3(X = Br, I) nanocrystals and chlorine-passivated PbSe CQDs, as demonstrated in Fig. 6. The solar cells made of the perovskite passivated PbSe CQDs exhibited a significant improvement in both the open-circuit voltage (VOC) and fill factor (FF). In addition,the mixed-perovskite passivated CQDs had stronger anti-oxidation capability, the PCE of the devices was retained by 90% after 57 days.In 2008, Hu et al[49]similarly demonstrated that the PCE performance can be further enhanced, due to the widened depletion layer and the reduced carrier recombination.

    Fig.6 Schematic diagram of ion exchange between chlorinated PbSe CQDs and CsPbX3 (X=Br, I)

    6.2 Epitaxial perovskite

    It has been reported that there is only a 5%mismatching in lattice between methylammonium lead triiodide (MAPbI3) perovskites and PbS CQDs[50]. Therefore, MAPbI3could be a promising candidate for the passivation of PbS CQDs. With density functional theory (DFT), Ning et al[51]calculated the interface formation energy between PbS (100) and MAPbI3(110) planes. They found that it was less than 10 meV/?2, suggesting that the growth of MAPbI3on PbS is as easy as the growth of PbS on PbS and MAPbI3on MAPbI3. Moreover,the lattices of MAPbI3and PbS CQDs are well matching in the both 3D and 2D configurations, as seen in Fig. 7 (a) and (b), respectively. Therefore,well-developed core-shell structures can be obtained through the epitaxial growth of MAPbI3on PbS CQDs. In addition, the DFT calculation also predicted that the epitaxial growth is not accompanied by interface defects, as illustrated in Fig. 7 (c) and (d)[51].

    Fig.7 Theoretical model of the perovskite epitaxially grown on CQDs. (a) Three-dimensional atomistic model of CQDs in a perovskite matrix, (b) Two-dimensional view of a single CQD in perovskite. The modeling of the crystal structure and interface of PbS and MAPbI3 showed that the MAPbI3 matched well with the PbS in the X-Z plane (c) and the X-Y plane (d).(The colors in the figure are as follows: grey-lead; yellow-sulfur; purple-iodine. The red dashes show the unit cell size and the yellow dashes are guides to the eye for matching planes) [51]

    In 2015, Yang et al[52]grow MAPbI3to passivate PbS CQDs, resulting in devices exhibiting a world record PCE of 8.95%, due to the reduced surface defect density and increased diffusion length.Together with the long diffusion length and high carrier mobility, the large bandgap of the perovskite ensured the generation of excitons in the CQDs with an efficiency of 80% from the photons and holes in the perovskite phase. The fact that the diffusion length of hybrid materials consisted of CQDs and perovskite grow in inverse proportion to CQDs content, suggesting that the perovskite could assist the charge transport in between the CQDs[16].Additionally, the CQDs are perfectly embedded in the matrix of perovskite so as to realize well-passivation for the CQDs’ surface, further preventing the photogenerated carriers from selfquenching effect[50]. Recently, Liu et al[53]boosted the PCE record to 12.6% by using halide-perovskite hybrid passivation technique. Meanwhile, the stability of the devices is large increased due to the suppression of the phase transition of the perovskite and the anti-oxidation capability of the CQDs was enhanced.

    Due to their unique properties, perovskites have been shown strong passivation capability to improve the photoelectrical performances of CQDs-based solar cells, no matter which method(i.e., mixing or epitaxial) is applied. Although the passivation of CQDs with perovskite has not been extensively studied, it strongly deserves for further exploration in the near future.

    7 Conclusions and Perspectives

    In recent years, more and more attentions have been paid to the synthesis and passivation of CQDs, while the related photovoltaic devices are still under development. It is necessary to further the output performance and stability of CQDs for large-scale practical applications. In this regard, we would like to propose two areas in the future studies.

    (1) Based on the flexibility of molecular engineering, it is suggested to high efficiency straight-chain planar organic ligands, with specific functional groups, which not only are able to passivate the CQDs and reduce the self-quenching problem, but also decrease the barrier of photon transport among the CQDs.

    (2) According to the composition and optical properties of CQDs, more high quality perovskites with lattice matching properties should be developed. By fully utilizing the high defect tolerance, high carrier mobility and long diffusion length of perovskites, both the photogenerated electron properties and the stabilities of the CQDs are expectedly improved for high performance solar cell applications.

    国产精品一区二区精品视频观看| 啦啦啦 在线观看视频| 亚洲三区欧美一区| 国产99久久九九免费精品| 欧美亚洲 丝袜 人妻 在线| 日本黄色日本黄色录像| 亚洲国产欧美日韩在线播放| 久久久久久久精品精品| 欧美日韩亚洲综合一区二区三区_| 777久久人妻少妇嫩草av网站| 正在播放国产对白刺激| 亚洲国产欧美一区二区综合| 精品一区二区三卡| 中文字幕精品免费在线观看视频| 日本wwww免费看| 80岁老熟妇乱子伦牲交| 麻豆乱淫一区二区| 亚洲欧洲精品一区二区精品久久久| 精品免费久久久久久久清纯 | 国产日韩欧美亚洲二区| 亚洲成人手机| 一进一出抽搐动态| 丝袜美腿诱惑在线| 精品亚洲乱码少妇综合久久| 免费一级毛片在线播放高清视频 | netflix在线观看网站| 操美女的视频在线观看| 色精品久久人妻99蜜桃| 国产精品久久久人人做人人爽| 久久久久久人人人人人| 欧美日韩视频精品一区| 亚洲av美国av| 99国产极品粉嫩在线观看| 少妇 在线观看| 91精品国产国语对白视频| 亚洲国产欧美在线一区| 青草久久国产| 欧美日韩亚洲综合一区二区三区_| 亚洲精品久久成人aⅴ小说| 国产日韩欧美视频二区| av电影中文网址| 成年人午夜在线观看视频| 黄色怎么调成土黄色| e午夜精品久久久久久久| 日韩欧美国产一区二区入口| 少妇猛男粗大的猛烈进出视频| 国产男女内射视频| 一级片'在线观看视频| 99精品久久久久人妻精品| 母亲3免费完整高清在线观看| 精品久久久久久久毛片微露脸 | 久久久欧美国产精品| 久久精品国产a三级三级三级| netflix在线观看网站| 黄色a级毛片大全视频| 亚洲国产欧美在线一区| 三级毛片av免费| 18在线观看网站| 国产有黄有色有爽视频| 国产伦理片在线播放av一区| 午夜影院在线不卡| 好男人电影高清在线观看| 国产视频一区二区在线看| 夜夜骑夜夜射夜夜干| 人人妻人人添人人爽欧美一区卜| 国产男人的电影天堂91| 在线观看免费日韩欧美大片| 亚洲性夜色夜夜综合| 岛国毛片在线播放| 国产在线观看jvid| 国产在线一区二区三区精| 97精品久久久久久久久久精品| 在线观看免费高清a一片| 多毛熟女@视频| 久久久国产成人免费| 精品福利永久在线观看| 亚洲国产日韩一区二区| 国产真人三级小视频在线观看| 在线亚洲精品国产二区图片欧美| 欧美性长视频在线观看| 久久青草综合色| 两个人看的免费小视频| 精品国内亚洲2022精品成人 | 我的亚洲天堂| 夫妻午夜视频| 性少妇av在线| 久久九九热精品免费| 亚洲一码二码三码区别大吗| 国产成人精品在线电影| 国产欧美日韩精品亚洲av| av在线老鸭窝| 午夜视频精品福利| 午夜两性在线视频| 国产精品99久久99久久久不卡| 91精品国产国语对白视频| 一本—道久久a久久精品蜜桃钙片| a级毛片在线看网站| 国产精品自产拍在线观看55亚洲 | 少妇裸体淫交视频免费看高清 | 欧美精品高潮呻吟av久久| 亚洲精品国产av成人精品| 成人18禁高潮啪啪吃奶动态图| 成人黄色视频免费在线看| 国产成人精品久久二区二区91| 捣出白浆h1v1| 免费少妇av软件| 男人舔女人的私密视频| 无限看片的www在线观看| 亚洲精品国产一区二区精华液| 国产熟女午夜一区二区三区| 久久国产精品大桥未久av| 亚洲欧美色中文字幕在线| 亚洲欧美成人综合另类久久久| 久久狼人影院| 婷婷色av中文字幕| 国产精品av久久久久免费| 亚洲视频免费观看视频| 久久久国产欧美日韩av| 老熟女久久久| 美女视频免费永久观看网站| 亚洲欧美激情在线| 波多野结衣av一区二区av| a级片在线免费高清观看视频| 精品人妻在线不人妻| 亚洲精品久久成人aⅴ小说| 亚洲av成人一区二区三| 美女主播在线视频| 国产精品成人在线| 视频在线观看一区二区三区| 亚洲七黄色美女视频| 欧美日韩亚洲综合一区二区三区_| 色94色欧美一区二区| 亚洲av美国av| 国产欧美日韩一区二区三 | 岛国毛片在线播放| 国产在线视频一区二区| 18禁国产床啪视频网站| 久久精品aⅴ一区二区三区四区| 欧美精品高潮呻吟av久久| 天天躁狠狠躁夜夜躁狠狠躁| av线在线观看网站| 成人av一区二区三区在线看 | 亚洲九九香蕉| 午夜福利免费观看在线| 午夜福利免费观看在线| 欧美+亚洲+日韩+国产| 午夜视频精品福利| 亚洲国产成人一精品久久久| 久久久久久久久免费视频了| 成人国语在线视频| 色精品久久人妻99蜜桃| 久久久久久久久久久久大奶| 满18在线观看网站| 高清黄色对白视频在线免费看| 最近最新中文字幕大全免费视频| 狠狠婷婷综合久久久久久88av| 精品国产一区二区三区久久久樱花| 国产一区二区三区在线臀色熟女 | 久久久欧美国产精品| 考比视频在线观看| 在线永久观看黄色视频| 国产又色又爽无遮挡免| 在线永久观看黄色视频| 欧美变态另类bdsm刘玥| 欧美黑人精品巨大| 国产又色又爽无遮挡免| 久久毛片免费看一区二区三区| 国产不卡av网站在线观看| 国产91精品成人一区二区三区 | 国产精品二区激情视频| 国产伦理片在线播放av一区| 国产精品久久久人人做人人爽| 精品人妻在线不人妻| 一区二区日韩欧美中文字幕| 美女午夜性视频免费| 亚洲欧美色中文字幕在线| 女人高潮潮喷娇喘18禁视频| 亚洲精品一区蜜桃| 日韩制服丝袜自拍偷拍| 老熟女久久久| www.自偷自拍.com| 亚洲专区中文字幕在线| 午夜精品国产一区二区电影| 国产一级毛片在线| 亚洲国产欧美日韩在线播放| 国产成人欧美| 老司机靠b影院| 精品国产超薄肉色丝袜足j| 日韩中文字幕欧美一区二区| 激情视频va一区二区三区| 啦啦啦啦在线视频资源| 亚洲国产欧美日韩在线播放| 亚洲精品在线美女| 婷婷色av中文字幕| 亚洲全国av大片| 男女无遮挡免费网站观看| 久久久欧美国产精品| 80岁老熟妇乱子伦牲交| 日韩熟女老妇一区二区性免费视频| 亚洲中文字幕日韩| 久久久精品94久久精品| 波多野结衣一区麻豆| 亚洲人成77777在线视频| 韩国精品一区二区三区| 国产成人免费无遮挡视频| 操美女的视频在线观看| 老司机影院毛片| 波多野结衣av一区二区av| 欧美日韩精品网址| 久久热在线av| 久久综合国产亚洲精品| 日韩大片免费观看网站| 亚洲精品中文字幕一二三四区 | 精品国产一区二区三区四区第35| 亚洲第一av免费看| a级片在线免费高清观看视频| 19禁男女啪啪无遮挡网站| 国产男女超爽视频在线观看| 精品国产乱码久久久久久男人| 纵有疾风起免费观看全集完整版| a级毛片在线看网站| 日本av免费视频播放| 久久久久视频综合| 欧美中文综合在线视频| 久久影院123| 波多野结衣av一区二区av| 国产免费av片在线观看野外av| 欧美黑人欧美精品刺激| 亚洲中文av在线| 日本a在线网址| 美女大奶头黄色视频| 国产色视频综合| 国产欧美日韩综合在线一区二区| 各种免费的搞黄视频| 国产高清videossex| 国产精品一区二区免费欧美 | 国产又色又爽无遮挡免| 久久精品人人爽人人爽视色| 黄频高清免费视频| 亚洲精品日韩在线中文字幕| 久久九九热精品免费| av片东京热男人的天堂| 午夜成年电影在线免费观看| 我的亚洲天堂| 免费一级毛片在线播放高清视频 | 国产在线一区二区三区精| 日韩欧美国产一区二区入口| 日韩视频在线欧美| 午夜福利,免费看| 90打野战视频偷拍视频| 高清黄色对白视频在线免费看| 欧美在线一区亚洲| 中国美女看黄片| 男人操女人黄网站| 日本wwww免费看| 久久久国产一区二区| 精品一区二区三区av网在线观看 | 国产av精品麻豆| 亚洲国产精品一区二区三区在线| 久久久久国内视频| 亚洲熟女精品中文字幕| 欧美日韩一级在线毛片| 桃花免费在线播放| 日本wwww免费看| 久久99一区二区三区| 美女午夜性视频免费| 激情视频va一区二区三区| 91九色精品人成在线观看| 国产精品一区二区在线不卡| 亚洲国产av新网站| 国产成人精品无人区| 欧美黑人欧美精品刺激| 男女午夜视频在线观看| 亚洲精品在线美女| 国产精品1区2区在线观看. | 丝袜在线中文字幕| 韩国精品一区二区三区| 久久狼人影院| 日韩,欧美,国产一区二区三区| 永久免费av网站大全| 成人手机av| 免费在线观看黄色视频的| 精品欧美一区二区三区在线| 国产成人av激情在线播放| 老司机亚洲免费影院| 国产精品影院久久| 亚洲av美国av| 久久精品国产亚洲av高清一级| 久久性视频一级片| 精品久久蜜臀av无| av网站在线播放免费| 欧美国产精品一级二级三级| 下体分泌物呈黄色| 91成人精品电影| 亚洲精品国产精品久久久不卡| 人成视频在线观看免费观看| 老司机午夜十八禁免费视频| 夜夜骑夜夜射夜夜干| 91字幕亚洲| 久久av网站| 伊人亚洲综合成人网| 99热网站在线观看| 欧美大码av| 亚洲av成人一区二区三| 每晚都被弄得嗷嗷叫到高潮| 两个人免费观看高清视频| 99精国产麻豆久久婷婷| 69精品国产乱码久久久| 久久久国产一区二区| 最新在线观看一区二区三区| 欧美在线黄色| 色94色欧美一区二区| 亚洲色图 男人天堂 中文字幕| 男女高潮啪啪啪动态图| 久久久久网色| 成人国产一区最新在线观看| 啦啦啦免费观看视频1| www.999成人在线观看| 日韩三级视频一区二区三区| 男女边摸边吃奶| 亚洲免费av在线视频| 国产成人av激情在线播放| 午夜福利影视在线免费观看| 老汉色∧v一级毛片| 国产亚洲欧美在线一区二区| 亚洲美女黄色视频免费看| 美女扒开内裤让男人捅视频| 亚洲中文日韩欧美视频| 啦啦啦啦在线视频资源| 日韩欧美一区二区三区在线观看 | 亚洲第一av免费看| 国产一区二区三区综合在线观看| 国产免费福利视频在线观看| 日韩有码中文字幕| 亚洲欧美日韩高清在线视频 | 精品卡一卡二卡四卡免费| 999精品在线视频| 久久狼人影院| 男女之事视频高清在线观看| 精品久久久久久电影网| 久久ye,这里只有精品| 99九九在线精品视频| 伊人久久大香线蕉亚洲五| 高清视频免费观看一区二区| 超色免费av| www.熟女人妻精品国产| 免费在线观看视频国产中文字幕亚洲 | 国产精品二区激情视频| 欧美日韩亚洲综合一区二区三区_| 精品国产乱码久久久久久小说| 两个人看的免费小视频| 欧美日韩av久久| 欧美变态另类bdsm刘玥| 男女免费视频国产| 亚洲精品乱久久久久久| av电影中文网址| 97在线人人人人妻| 国产男女超爽视频在线观看| 中文字幕人妻熟女乱码| 亚洲国产精品一区三区| 秋霞在线观看毛片| 久久精品国产亚洲av香蕉五月 | 免费av中文字幕在线| a级毛片黄视频| 啦啦啦免费观看视频1| 久久国产精品大桥未久av| 亚洲欧美成人综合另类久久久| xxxhd国产人妻xxx| 欧美日韩黄片免| 亚洲精品美女久久久久99蜜臀| 一级,二级,三级黄色视频| 国产高清videossex| 亚洲va日本ⅴa欧美va伊人久久 | 国产精品久久久人人做人人爽| 人成视频在线观看免费观看| 大片电影免费在线观看免费| 欧美国产精品va在线观看不卡| 婷婷色av中文字幕| 亚洲视频免费观看视频| 这个男人来自地球电影免费观看| 亚洲国产中文字幕在线视频| a级毛片黄视频| 日韩电影二区| 国产精品久久久久久人妻精品电影 | 两个人免费观看高清视频| 久久中文字幕一级| 女人精品久久久久毛片| 国产1区2区3区精品| 亚洲精品第二区| 美女中出高潮动态图| 国产成人精品久久二区二区91| 欧美黄色淫秽网站| netflix在线观看网站| 国产欧美日韩一区二区三区在线| 国产精品久久久人人做人人爽| 亚洲国产欧美一区二区综合| 国产男女内射视频| 久久久久网色| 久久久精品免费免费高清| 男女边摸边吃奶| 久久久精品94久久精品| 一级a爱视频在线免费观看| 1024香蕉在线观看| 视频在线观看一区二区三区| 男女高潮啪啪啪动态图| 久久久久国产精品人妻一区二区| 考比视频在线观看| 日本一区二区免费在线视频| 午夜福利视频精品| 亚洲伊人色综图| 国产成人精品在线电影| 亚洲国产av新网站| 丰满少妇做爰视频| 日韩熟女老妇一区二区性免费视频| av网站免费在线观看视频| 美女扒开内裤让男人捅视频| 五月天丁香电影| 精品乱码久久久久久99久播| 国产av又大| 精品高清国产在线一区| 国产一区有黄有色的免费视频| 久久久久久久久久久久大奶| 欧美久久黑人一区二区| 天天躁夜夜躁狠狠躁躁| 性色av乱码一区二区三区2| 一级毛片电影观看| 999久久久精品免费观看国产| 亚洲男人天堂网一区| 国产一区二区在线观看av| 免费黄频网站在线观看国产| 亚洲专区中文字幕在线| 中文字幕另类日韩欧美亚洲嫩草| 免费av中文字幕在线| 悠悠久久av| 国产有黄有色有爽视频| 精品一区在线观看国产| 亚洲精品国产av蜜桃| 男女免费视频国产| 人人妻人人添人人爽欧美一区卜| 久久精品国产a三级三级三级| 久久精品成人免费网站| 亚洲精品久久午夜乱码| 99国产极品粉嫩在线观看| 精品福利永久在线观看| 淫妇啪啪啪对白视频 | 99精品欧美一区二区三区四区| av片东京热男人的天堂| 欧美日韩av久久| 19禁男女啪啪无遮挡网站| 国产精品亚洲av一区麻豆| 亚洲五月色婷婷综合| 国产亚洲欧美在线一区二区| 亚洲第一欧美日韩一区二区三区 | 欧美中文综合在线视频| 久久久久久免费高清国产稀缺| 老司机影院毛片| svipshipincom国产片| 老司机靠b影院| 久久中文字幕一级| 欧美另类一区| 乱人伦中国视频| 人成视频在线观看免费观看| 人人妻人人添人人爽欧美一区卜| 乱人伦中国视频| 色精品久久人妻99蜜桃| 免费一级毛片在线播放高清视频 | 欧美另类亚洲清纯唯美| 婷婷色av中文字幕| 亚洲欧美一区二区三区黑人| 亚洲国产精品一区三区| 国产野战对白在线观看| 十八禁人妻一区二区| 一本久久精品| 欧美黄色片欧美黄色片| 国产97色在线日韩免费| 性色av一级| 美女高潮到喷水免费观看| 别揉我奶头~嗯~啊~动态视频 | 午夜福利影视在线免费观看| 一级a爱视频在线免费观看| 亚洲精品一卡2卡三卡4卡5卡 | 国产精品久久久久久精品古装| 欧美日韩精品网址| 欧美97在线视频| 成年人黄色毛片网站| 91九色精品人成在线观看| 精品乱码久久久久久99久播| 两人在一起打扑克的视频| 妹子高潮喷水视频| 大型av网站在线播放| 啦啦啦在线免费观看视频4| 国产免费av片在线观看野外av| 国产一区二区在线观看av| 午夜两性在线视频| 亚洲欧美精品自产自拍| 久久国产亚洲av麻豆专区| 精品国产一区二区三区四区第35| 日韩有码中文字幕| 久久国产精品影院| 最近中文字幕2019免费版| 精品第一国产精品| 国产日韩欧美在线精品| 欧美日韩一级在线毛片| 欧美精品亚洲一区二区| 色94色欧美一区二区| av一本久久久久| 亚洲第一av免费看| 18禁黄网站禁片午夜丰满| 97精品久久久久久久久久精品| 久久中文字幕一级| 亚洲色图综合在线观看| 久久精品熟女亚洲av麻豆精品| 在线观看免费午夜福利视频| 水蜜桃什么品种好| 黑丝袜美女国产一区| 久久综合国产亚洲精品| h视频一区二区三区| 最新在线观看一区二区三区| 少妇粗大呻吟视频| 丝袜人妻中文字幕| 五月天丁香电影| 成人亚洲精品一区在线观看| 人人澡人人妻人| 黄片小视频在线播放| 法律面前人人平等表现在哪些方面 | 国产野战对白在线观看| 免费高清在线观看视频在线观看| 丰满少妇做爰视频| 在线天堂中文资源库| 国产黄频视频在线观看| 欧美日韩精品网址| 中文字幕人妻丝袜制服| 热re99久久国产66热| 欧美黄色片欧美黄色片| www.熟女人妻精品国产| 啦啦啦免费观看视频1| 一进一出抽搐动态| 黄色 视频免费看| 欧美亚洲 丝袜 人妻 在线| 夜夜骑夜夜射夜夜干| 久久女婷五月综合色啪小说| 天堂8中文在线网| 欧美变态另类bdsm刘玥| 一级片'在线观看视频| 男女午夜视频在线观看| 视频区图区小说| 欧美 日韩 精品 国产| 国产一区二区三区av在线| 侵犯人妻中文字幕一二三四区| 亚洲七黄色美女视频| 一本大道久久a久久精品| 午夜福利免费观看在线| 免费在线观看日本一区| 热99久久久久精品小说推荐| 欧美日韩亚洲国产一区二区在线观看 | 久久精品亚洲熟妇少妇任你| 国产亚洲欧美在线一区二区| 天堂8中文在线网| 亚洲精品一二三| 男女国产视频网站| 国产在线观看jvid| 日韩中文字幕视频在线看片| 久久久久久人人人人人| 黄片大片在线免费观看| 成年人午夜在线观看视频| 免费高清在线观看日韩| 丁香六月欧美| 99精品欧美一区二区三区四区| 国产高清videossex| 久久精品国产亚洲av香蕉五月 | 日韩一区二区三区影片| 中亚洲国语对白在线视频| 一本综合久久免费| 亚洲九九香蕉| 一区二区三区乱码不卡18| 91精品三级在线观看| 人人澡人人妻人| 99re6热这里在线精品视频| 国产精品一区二区免费欧美 | 亚洲avbb在线观看| 国产xxxxx性猛交| 777米奇影视久久| 免费少妇av软件| 久久久久国产一级毛片高清牌| 女人高潮潮喷娇喘18禁视频| 日本wwww免费看| 午夜免费成人在线视频| 精品一区二区三区四区五区乱码| 男人舔女人的私密视频| 最黄视频免费看| 老熟妇仑乱视频hdxx| 人人妻人人澡人人看| 伊人久久大香线蕉亚洲五| 午夜老司机福利片| 丝瓜视频免费看黄片| 在线观看免费午夜福利视频| 三上悠亚av全集在线观看| 日韩有码中文字幕| 91字幕亚洲| 日本vs欧美在线观看视频| 精品亚洲成a人片在线观看| 精品一区二区三区四区五区乱码| 日韩欧美国产一区二区入口| 亚洲国产av新网站| 亚洲少妇的诱惑av| 国产成人欧美在线观看 | 少妇人妻久久综合中文| 人人妻,人人澡人人爽秒播| 亚洲免费av在线视频| 午夜影院在线不卡| 国产男人的电影天堂91| av欧美777| av天堂久久9| 91精品三级在线观看| 啦啦啦在线免费观看视频4|