• <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 ?

    Ultrafast interlayer photocarrier transfer in graphene–MoSe2 van der Waals heterostructure?

    2017-08-30 08:26:26XinWuZhang張心悟DaWeiHe何大偉JiaQiHe何佳琪SiQiZhao趙思淇ShengCaiHao郝生財YongShengWang王永生andLiXinYi衣立新
    Chinese Physics B 2017年9期
    關(guān)鍵詞:大偉

    Xin-Wu Zhang(張心悟),Da-Wei He(何大偉),Jia-Qi He(何佳琪),Si-Qi Zhao(趙思淇),Sheng-Cai Hao(郝生財), Yong-Sheng Wang(王永生),and Li-Xin Yi(衣立新)

    Key Laboratory of Luminescence and Optical Information,Ministry of Education,Institute of Optoelectronic Technology,

    Beijing Jiaotong University,Beijing 100044,China

    Ultrafast interlayer photocarrier transfer in graphene–MoSe2van der Waals heterostructure?

    Xin-Wu Zhang(張心悟),Da-Wei He(何大偉),Jia-Qi He(何佳琪),Si-Qi Zhao(趙思淇),Sheng-Cai Hao(郝生財), Yong-Sheng Wang(王永生),and Li-Xin Yi(衣立新)?

    Key Laboratory of Luminescence and Optical Information,Ministry of Education,Institute of Optoelectronic Technology,

    Beijing Jiaotong University,Beijing 100044,China

    We report the fabrication and photocarrier dynamics in graphene–MoSe2heterostructures.The samples were fabricated by mechanical exfoliation and manual stacking techniques.Ultrafast laser measurements were performed on the heterostructure and MoSe2monolayer samples.By comparing the results,we conclude that photocarriers injected in MoSe2of the heterostructure transfer to graphene on an ultrafast time scale.The carriers in graphene alter the optical absorption coefficient of MoSe2.These results illustrate the potential applications of this material in optoelectronic devices.

    van der Waals heterostructure,transition metal dichalcogenides,molybdenum diselenide,transient absorption

    1.Introduction

    The discovery of graphene in 2004[1,2]has stimulated extensive studies on its novel property and potential applications. Graphene is formed by a single layer of carbon atoms bound together in a hexagonal lattice.Due to its unique structure, graphene has many superior properties,such as high Young’s modulus and fracture strength,[3]high thermal conductivity,[4]ultrafast dynamic optical properties,[5]and high charge carrier mobility.[1]These properties make graphene an attractive candidate for various applications,such as ultracapacitors,[6,7]solar cells,[8–11]photodetector,[12]and low-power-consumption electronics.[13,14]However,the lack of a bandgap limited its application in logic electronic devices.Furthermore,its relatively small optical absorbance is also a drawback for optoelectronic applications.Monolayer transition metal dichalcogenides(TMDs),on the other hand,have remarkably high absorbance in the visible range[15]and a sizable bandgap.[16,17]However,their charge carrier mobilities are relatively low. Hence,combining graphene and TMD can potentially produce bi-layer materials that can effectively absorb light and transfer charge carriers,which are two key elements for most optoelectronic applications.

    Indeed,very recently,significant progress has been made in studies of graphene–TMD heterostructures.So far,most studies have focused on combining graphene with MoS2. Initially,such heterostructures were fabricated by manually stacking graphene and MoS2monolayers together.[18]Mechanical properties of graphene–MoS2were studied both theoretically and experimentally.[19,20]The electronic structure of the formed heterostructure was calculated,measured,and controlled.[21–26]For electronic applications,tunneling transistors have been demonstrated with MoS2serving as the tunneling barrier.[18,27–33]

    Besides these investigations on graphene–MoS2,heterostructure formed by graphene and tungsten based TMD monolayers has also been studied.For graphene–WS2,spin–orbit interaction[34]and various applications have been attempted,such as tunneling transistors,[29,35]photovoltaics,[36]light-emitting diodes,[37]and photodetection.[38]Measurements of its band alignment,[39]photoluminescence properties,[40]and light-emitting devices[37]have been reported.

    In contrast to these extensive efforts on developing heterostructures formed by graphene and MoS2and WS2,MoSe2has been seldom used to form heterostructures with graphene. The only reports on graphene–MoSe2heterostructures are their molecular beam expitaxy[41]and observation of photoluminescence quenching.[42]MoSe2possesses several properties that make it an attractive member of TMDs.It has a direct optical bandgap of 1.55 eV,[43]which is near the optimal bandgap of single-junction photovoltaic devices and photocatalysis.[44–46]

    Here we report fabrication of graphene–MoSe2heterostructures and ultrafast laser measurements on photocarrier dynamics.We observed efficient carrier transfer from MoSe2to graphene,and strong effect of carriers in graphene on optical properties of MoSe2.These results indicate that graphene–MoSe2heterostructures are promising materials for optoelectronic applications.

    2.Experiment

    Graphene and MoSe2flakes were fabricated by mechanical exfoliation.Adhesive tapes were used to mechanically exfoliate flakes from bulk crystals onto polydimethylsiloxane (PDMS)substrates.The monolayers were identified by optical contrasts with an optical microscope.Then a MoSe2monolayer flake was transferred to a Si substrate with a 90 nm SiO2layer and annealed for 2 h at 200°C in an Ar(60 sccm) environment with a pressure of 3 Torr.Next,a graphene flake was transferred onto the MoSe2flake,followed by the same annealing procedure.The final optical microscope image of the sample is shown in Fig.1(a),where the graphene–MoSe2heterostructure is in the triangle yellow area.Figure 1(b)illustrates the predicted band alignment[47,48]of the heterostructure.We note that the band gap of MoSe2presented in Fig.1(b)is a theoretical value,which is different from that of the experiment and has no influence on the measurement.

    Fig.1.(color online)(a)Microscope images of the samples studied.(b)Band alignment of graphene and MoSe2 monolayers.(c)Experimental setup to measure differential reflectivity.

    In the transient absorption microscopy setup shown as Fig.1(c),a passively mode-locked Ti:sapphire oscillator was used to generate a 100 fs pulse with a central wavelength of 790 nm at 80 MHz.We used a beamsplitter to separate the pulse into two beams.One of the beams was coupled to a photonic crystal fiber to generate supercontinuum.A bandpassfilter with a passing wavelength of 620 nm and a bandwidth of 10 nm was employed to select a 620 nm pulse from the super continuum,which served as the pump.Combined with the other beam probe which was outputted directly from the oscillator,the two beams were finally focused onto the sample by a microscope objective lens.The reflected probe was collimated by the objective lens and measured by one detector of a balanced detector.A portion of the probe beam was taken as a reference beam,which is sent to the other detector of the balanced detector.A lock-in amplifier was used to measure the voltage output of the detector.A mechanical chopper was placed in the pump arm to modulate the intensity of the pump beam at about 2 kHz.Hence,the balanced detector now outputs a voltage that is proportional to a differential reflectivity of the probe,R/R0.It is defined as the relative change of the probe reflectivity caused by the pump,(R-R0)/R0,where R and R0are the reflectivity of the probe with the pump presence and without it,respectively.All the measurements were performed at room temperature with the sample exposed in air.

    3.Results and discussion

    We first studied a MoSe2monolayer sample.A pump pulse of 2.00 eV was used to inject photocarriers.A probe pulse of 1.57 eV,which is tuned near to the exciton resonance of MoSe2,was used to monitor these photocarriers.The top panel of Fig.2(a)shows the differential reflectivity signal as a function of the probe delay.In this measurement,the pump fluence is 4.9μJ/cm2.By using an absorption coeffi-cient of 2×105cm?1for MoSe2monolayer at the probe photon energy,[49]an injected carrier density of 2.1×1010cm?2was established.A peak differential reflectivity signal of 1.14×10?4was observed.Furthermore,the decay of the signal can be fitted by a bi-exponential function,with two time constants of 22 and 125 ps,respectively.The rest of Fig.2(a) shows the measured signal at different pump fluences.By fitting these data,we found that as the pump fluence decreased, the fast decay component characterized by 22 ps becomes less pronounced.Based on this feature,we can attribute the long time constant of 125 ps to the photocarrier lifetime in MoSe2. The fast decay channel at higher fluence can be attributed to the contribution of exciton–exciton annihilation.[50]

    Figure 2(b)summarizes the peak differential reflectivity signal as a function of the pump fluence.A linear relation is clearly observed,as confirmed by the linear fit(red line). Finally,with a fixed pump fluence of 1.23μJ/cm2,we repeated the measurement with different probe photon energies. Figure 2(c)shows the peak differential reflectivity signal as a function of the probe photon energy.The peak signal was observed at a probe photon energy of 1.57 eV,which is well consistent with the previously determined optical bandgap of MoSe2monolayers.This observation shows that the probe pulse senses the photocarriers via the change of the excitonic absorption peak induced by these carriers.

    Figure 3 shows the results of the same measurement performed with the graphene–MoSe2heterostructure.If there was no interlayer photocarrier transfer or no interlayer coupling, the results should have been similar to those shown in Fig.2. Due to the smaller absorption coefficient of graphene compared to MoSe2,the carriers injected in graphene can be neglected for simplicity,and the pump pulse can be assumed to inject the same carrier density in the MoSe2of the heterostructure as the MoSe2monolayer.However,we observed two dramatic differences between the two measurements.First, the signal magnitude is about a factor of 10 larger in the heterostructure sample under the same conditions.Second,the signal decays rapidly compared to the MoSe2monolayer.Exponential fits(blue curves)produced a decay time constant of 8.5 ps.Meanwhile,similar dependences on the pump fluence and probe photon energy are observed.

    We attribute these observed features to two physical mechanisms.First,the photocarriers excited in MoSe2rapidly transfer to graphene.Second,the carriers in graphene can induce a differential reflectivity signal of the probe tuned to the MoSe2resonance.

    Fig.2.(color online)Differential reflectivity measurement of monolayer MoSe2.(a)Differential reflectivity signal as a function of probe delay with pump fluences of(from top to bottom)4.9,4.29,3.06,2.45,1.84,1.23 and 0.61μJ/cm2,respectively.The red curves are exponential fits.(b)Peak differential reflectivity signal as a function of pump fluence.(c)Peak differential reflectivity signal as a function of the probe photon energy.

    Fig.3.(color online)Differential reflectivity measurement of graphene–MoSe2 heterostructure.(a)Differential reflectivity signal as a function of probe delay with pump fluences of(from top to bottom)4.9,4.29,3.06,2.45,1.84 and 1.23μJ/cm2,respectively.The blue curves are exponential fits.(b)Peak differential reflectivity signal as a function of pump fluence.(c)Peak differential reflectivity signal as a function of the probe photon energy.

    Fig.4.The electric field of the excitons in MoSe2 before and after forming the heterostruture.

    The strong dependence of the peak signal on probe photon energy indicates that the signal originates from a change of the absorption coefficient of MoSe2.However,this change cannot be induced by the photocarriers in MoSe2,since in the measurements on MoSe2monolayer(Fig.2),we have established the magnitude of the signal for such photocarrier densities used in the measurements.The signal is too large to be attributed to photocarriers in MoSe2.Furthermore,the decay of the signal is very fast.Since the lifetime of photocarriers in graphene was known to be on the same time scale,this further indicates that the signal monitors the carriers in graphene, instead of MoSe2.

    We assume that the mechanism for change of the absorption coefficient of MoSe2by carriers in graphene is via a screening effect of these carriers on the electric field of the excitons.It has been well established that the Coulomb interaction between electrons and holes in monolayer TMDs is significantly enhanced by the reduced dielectric screening. As shown in Fig.4,the majority of the field lines are in the vacuum surrounding the monolayer.This effect has resulted in extremely large exciton binding energies in these materials.When combined with a graphene layer,the carriers in graphene can screen the fields in that layer,and hence change the interaction between the electrons and holes in excitons.

    Therefore,our results provide quantitative information on the physics mechanism of screening of graphene on manybody interactions in MoSe2monolayers.In particular,it is possible to control the electron–hole interaction in MoSe2,as well as other 2D materials,by interfacing with graphene with a certain thickness.This opens up the opportunities of controlling electron–hole interactions in van der Waals materials.

    Based on this mechanism and the fast decay of the signal observed in Fig.3,as well as the lack of a long-lived signal,we conclude that photocarriers excited in MoSe2rapidly transfer to graphene.These carriers in graphene can alter the absorption of MoSe2.

    The observed effects have important implications on using these materials in optoelectronic devices.For example, the efficient transfer of photocarriers from MoSe2to graphene suggests that such bilayers can be used in photodetectors and solar cells.MoSe2has a large absorption coefficient at optimal wavelength for solar cells,while graphene possesses superior charge transport performance.The bilayer structure effectively combines these advantages.The demonstrated control of MoSe2absorption by carriers in graphene can be utilized in light modulation applications where gate controlled carriers in graphene can be used to modulate absorption of light by MoSe2.

    4.Conclusion

    We have fabricated a less investigated graphene–MoSe2heterostructure,and studied its photocarrier dynamics.We found that photocarriers injected in MoSe2transfer to graphene on an ultrafast time scale.We also found that a carrierin graphene can change the excitonic absorption ofMoSe2, which can be potentially used for electric control of optical absorption of MoSe2.Ourresults illustrate thatgraphene–MoSe2heterostructures can effectively combine the novel optical absorption property of MoSe2and charge the transport property of graphene,for potential applications in optoelectronic devices.

    [1]Novoselov K S,Geim A K,Morozov S V,Jiang D,Zhang Y,Dubonos S V,Grigorieva I V and Firsov A A 2004 Science 306 666

    [2]Novoselov K S,Geim A K,Morozov S V,Jiang D,Katsnelson M I, Grigorieva I V,Dubonos S V and Firsov A A 2005 Nature 438 197

    [3]Lee C,Wei X,Kysar J W and Hone J 2008 Science 321 385

    [4]Balandin A A,Ghosh S,Bao W,Calizo I,Teweldebrhan D,Miao F and Lau C N 2008 Nano Lett.8 902

    [5]Jin Q,Dong HM,Han Kand Wang XF 2015 Acta Phys.Sin.64 237801 (in Chinese)

    [6]Stoller M D,Park S,Zhu Y,An J and Ruoff R S 2008 Nano Lett.8 3498

    [7]Pan D,Wang S,Zhao B,Wu M,Zhang H,Wang Y and Jiao Z 2009 Chem.Mater.21 3136

    [8]Becerril H A,Mao J,Liu Z,Stoltenberg R M,Bao Z and Chen Y 2008 ACS Nano 2 463

    [9]Chen H,Müller M B,Gilmore K J,Wallace G G and Li D 2008 Adv. Mater.20 3557

    [10]Wang X,Zhi L and Müllen K 2008 Nano Lett.8 323

    [11]Liu Z,Liu Q,Huang Y,Ma Y,Yin S,Zhang X,Sun W and Chen Y 2008 Adv.Mater.20 3924

    [12]Liang Z J,Liu H X,Niu Y X and Yin Y H 2016 Acta Phys.Sin.65 138501(in Chinese)

    [13]Geim A K and Novoselov K S 2007 Nat.Mater.6 183

    [14]Geim A K 2009 Science 324 1530

    [15]Liu H L,Shen C C,Su S H,Hsu C L,Li M Y and Li L J 2014 Appl. Phys.Lett.105 201905

    [16]He K,Kumar N,Zhao L,Wang Z,Mak K F,Zhao H and Shan J 2014 Phys.Rev.Lett.113 026803

    [17]Zeng F,Zhang W B and Tang B Y 2015 Chin.Phys.B 24 097103

    [18]Britnell L,Gorbachev R,Jalil R,Belle B,Schedin F,Mishchenko A, Georgiou T,Katsnelson M,Eaves L and Morozov S 2012 Science 335 947

    [19]Jiang J W and Park H S 2014 Appl.Phys.Lett.105 033108

    [20]Elder R M,Neupane M R and Chantawansri T L 2015 Appl.Phys.Lett. 107 073101

    [21]Ebnonnasir A,Narayanan B,Kodambaka S and Ciobanu C V 2014 Appl.Phys.Lett.105 031603

    [22]Coy Diaz H,Avila J,Chen C,Addou R,Asensio M C and Batzill M 2015 Nano Lett.15 1135

    [23]Jin W,Yeh P C,Zaki N,Chenet D,Arefe G,Hao Y,Sala A,Mentes T O,Dadap J I and Locatelli A 2015 Phys.Rev.B 92 201409

    [24]Pierucci D,Henck H,Avila J,Balan A,Naylor C H,Patriarche G, Dappe Y J,Silly M G,Sirotti F and Johnson A C 2016 Nano Lett. 16 4054

    [25]Ulstrup S,?abo A G,Miwa J A,Riley J M,Gr?nborg S S,Johannsen J C,Cacho C,Alexander O,Chapman R T and Springate E 2016 ACS Nano 10 6315

    [26]Wei Y,Ma XG,Zhu L,He H and Huang CY 2017 Acta Phys.Sin.66 087101(in Chinese)

    [27]Yu W J,Li Z,Zhou H,Chen Y,Wang Y,Huang Y and Duan X 2013 Nat.Mater.12 246

    [28]Moriya R,Yamaguchi T,Inoue Y,Morikawa S,Sata Y,Masubuchi S and Machida T 2014 Appl.Phys.Lett.105 083119

    [29]Yamaguchi T,Moriya R,Inoue Y,Morikawa S,Masubuchi S,Watanabe K,Taniguchi T and Machida T 2014 Appl.Phys.Lett.105 223109

    [30]Zhang W,Chuu C P,Huang J K,Chen C H,Tsai M L,Chang Y H, Liang C T,Chen Y Z,Chueh Y L and He J H 2014 Sci.Rep.4 3826

    [31]Moriya R,Yamaguchi T,Inoue Y,Sata Y,Morikawa S,Masubuchi S and Machida T 2015 Appl.Phys.Lett.106 223103

    [32]Sata Y,Moriya R,Morikawa S,Yabuki N,Masubuchi S and Machida T 2015 Appl.Phys.Lett.107 023109

    [33]Joiner C A,Campbell P M,Tarasov A A,Beatty B R,Perini C J,Tsai M Y,Ready W J and Vogel E M 2016 ACS Appl.Mater.Inter.8 8702

    [34]Wang Z,Ki D K,Chen H,Berger H,MacDonald A H and Morpurgo A F 2015 Nat.Commun.6 9339

    [35]Georgiou T,Jalil R,Belle B D,Britnell L,Gorbachev R V,Morozov S V,Kim YJ,Gholinia A,Haigh S J and Makarovsky O 2013 Nat. Nanotechnol.8 100

    [36]Shanmugam M,Jacobs-Gedrim R,Song E S and Yu B 2014 Nanoscale 6 12682

    [37]Withers F,Del Pozo-Zamudio O,Mishchenko A,Rooney A,Gholinia A,Watanabe K,Taniguchi T,Haigh S,Geim A and Tartakovskii A 2015 Nat.Mater.14 301

    [38]Tan H,Fan Y,Zhou Y,Chen Q,Xu W and Warner J H 2016 ACS Nano 10 7866

    [39]Kim K,Larentis S,Fallahazad B,Lee K,Xue J,Dillen D C,Corbet C M and Tutuc E 2015 ACS Nano 9 4527

    [40]Li Y,Qin J K,Xu C Y,Cao J,Sun Z Y,Ma L P,Hu PA,Ren W C and Zhen L 2016 Adv.Funct.Mater.26 4319

    [41]Vishwanath S,Liu X,Rouvimov S,Mende P C,Azcatl A,McDonnell S,Wallace R M,Feenstra R M,Furdyna J K and Jena D 2015 2D Mater. 2 024007

    [42]Shim G W,Yoo K,Seo S B,Shin J,Jung D Y,Kang I S,Ahn C W,Cho B J and Choi S Y 2014 ACS Nano 8 6655

    [43]Ji J T,Zhang A M,Xia T L,Gao P,Jie Y H,Zhang Q and Zhang Q M 2016 Chin.Phys.B 25 077802

    [44]Shin B,Zhu Y,Bojarczuk N A,Chey S J and Guha S 2012 Appl.Phys. Lett.101 053903

    [45]Shin B,Bojarczuk N A and Guha S 2013 Appl.Phys.Lett.102 091907

    [46]Shi Y,Hua C,Li B,Fang X,Yao C,Zhang Y,Hu Y S,Wang Z,Chen L and Zhao D 2013 Adv.Funct.Mater.23 1832

    [47]Guo Y and Robertson J 2016 Appl.Phys.Lett.108 233104

    [48]Yu YJ,Zhao Y,Ryu S,Brus L E,Kim K S and Kim P 2009 Nano Lett. 9 3430

    [49]Beal A R and Hughes H P 1979 J.Phys.C:Solid State Phys.12 881

    [50]Kumar N,Cui Q,Ceballos F,He D,Wang Y and Zhao H 2014 Phys. Rev.B 89 125427

    28 April 2017;revised manuscript

    11 June 2017;published online 31 July 2017)

    10.1088/1674-1056/26/9/097202

    ?Project supported by the National Natural Science Foundation of China(Grant Nos.61275058,61527817,61335006,and 61378073),the National Science Foundation,China(Grant No.DMR-1505852),the National Basic Research Program of China(Grant Nos.2016YFA0202300 and 2016YFA0202302),and Beijing Science and Technology Committee,China(Grant No.Z151100003315006).

    ?Corresponding author.E-mail:lxyi@bjtu.edu.cn

    ?2017 Chinese Physical Society and IOP Publishing Ltd http://iopscience.iop.org/cpb http://cpb.iphy.ac.cn

    猜你喜歡
    大偉
    張大偉作品
    Investigating the thermal conductivity of materials by analyzing the temperature distribution in diamond anvils cell under high pressure
    Ghost imaging-based optical cryptosystem for multiple images using integral property of the Fourier transform?
    Enhanced microwave absorption performance of MOF-derived hollow Zn-Co/C anchored on reduced graphene oxide?
    為你守候
    歌海(2021年2期)2021-06-22 01:58:38
    一又四分之三
    短篇小說(2021年9期)2021-06-06 09:53:18
    神奇的邊界線:一不留神就出國
    智慧少年(2017年8期)2018-01-10 21:39:12
    第三十一個蛋
    貨比三家VS 嘗遍五味
    愛你(2015年8期)2015-11-15 03:31:13
    不會說話
    故事會(2015年2期)2015-02-26 01:10:34
    欧美日韩福利视频一区二区| 麻豆成人午夜福利视频| av在线天堂中文字幕| 亚洲人成77777在线视频| 国产三级黄色录像| 51午夜福利影视在线观看| 少妇裸体淫交视频免费看高清 | 精品日产1卡2卡| 桃色一区二区三区在线观看| 很黄的视频免费| 在线观看免费午夜福利视频| 天天躁狠狠躁夜夜躁狠狠躁| 欧美一区二区精品小视频在线| 久久婷婷成人综合色麻豆| 一边摸一边做爽爽视频免费| 激情在线观看视频在线高清| 亚洲av成人不卡在线观看播放网| 久久久国产精品麻豆| 真人一进一出gif抽搐免费| 日韩一卡2卡3卡4卡2021年| 日本 欧美在线| 在线播放国产精品三级| 久久香蕉激情| 欧美色欧美亚洲另类二区| 91麻豆av在线| 国产片内射在线| 一级毛片女人18水好多| 看黄色毛片网站| 女性被躁到高潮视频| 亚洲 欧美 日韩 在线 免费| 波多野结衣高清无吗| av欧美777| 国产av不卡久久| 欧美成人性av电影在线观看| 99riav亚洲国产免费| 热99re8久久精品国产| 日本撒尿小便嘘嘘汇集6| 在线播放国产精品三级| 人人妻人人看人人澡| 亚洲欧美精品综合一区二区三区| 熟女电影av网| 久久久久久九九精品二区国产 | 级片在线观看| 成人三级做爰电影| 操出白浆在线播放| 国产成人影院久久av| 欧美日韩亚洲国产一区二区在线观看| 欧美不卡视频在线免费观看 | 成人亚洲精品一区在线观看| 国产97色在线日韩免费| 99久久99久久久精品蜜桃| 欧美一区二区精品小视频在线| 亚洲av成人av| 18禁黄网站禁片午夜丰满| 可以在线观看毛片的网站| 国产一级毛片七仙女欲春2 | 欧美激情久久久久久爽电影| 亚洲国产看品久久| 日韩高清综合在线| 久久青草综合色| 麻豆久久精品国产亚洲av| 国产精品,欧美在线| 麻豆av在线久日| 欧美国产日韩亚洲一区| 国产亚洲av高清不卡| 亚洲激情在线av| 亚洲精品久久国产高清桃花| 国内精品久久久久精免费| 亚洲中文字幕日韩| 啦啦啦 在线观看视频| 欧美日韩一级在线毛片| 黄色毛片三级朝国网站| 婷婷精品国产亚洲av在线| 天天添夜夜摸| 成年女人毛片免费观看观看9| 免费在线观看视频国产中文字幕亚洲| 一区福利在线观看| 欧美黑人巨大hd| 无人区码免费观看不卡| 欧美中文综合在线视频| 夜夜看夜夜爽夜夜摸| 免费av毛片视频| 18禁美女被吸乳视频| 色精品久久人妻99蜜桃| 国内久久婷婷六月综合欲色啪| 两个人看的免费小视频| 身体一侧抽搐| 成在线人永久免费视频| 亚洲成国产人片在线观看| 国产成+人综合+亚洲专区| 女人高潮潮喷娇喘18禁视频| 日韩欧美免费精品| 法律面前人人平等表现在哪些方面| 色老头精品视频在线观看| 一a级毛片在线观看| 日本 欧美在线| 国产人伦9x9x在线观看| 国产亚洲精品久久久久久毛片| 香蕉av资源在线| 久久性视频一级片| 中文字幕久久专区| 午夜影院日韩av| 搡老妇女老女人老熟妇| 老司机午夜十八禁免费视频| 欧美黄色淫秽网站| 一本综合久久免费| 日日摸夜夜添夜夜添小说| 欧美日韩精品网址| 国产亚洲精品第一综合不卡| 久久久久久久午夜电影| 亚洲五月婷婷丁香| 亚洲欧美激情综合另类| 国产精品 欧美亚洲| 亚洲自偷自拍图片 自拍| 日本五十路高清| 久久香蕉国产精品| av超薄肉色丝袜交足视频| 免费在线观看亚洲国产| a在线观看视频网站| 一本一本综合久久| 欧美日韩一级在线毛片| 精品午夜福利视频在线观看一区| 十分钟在线观看高清视频www| 一本久久中文字幕| 欧美成人一区二区免费高清观看 | 国产一区二区三区在线臀色熟女| 免费人成视频x8x8入口观看| 制服诱惑二区| 热99re8久久精品国产| 麻豆国产av国片精品| 人妻久久中文字幕网| 黄片播放在线免费| 国产人伦9x9x在线观看| 亚洲精品国产一区二区精华液| 国产av一区在线观看免费| 免费在线观看日本一区| 老司机在亚洲福利影院| 又黄又爽又免费观看的视频| 老熟妇仑乱视频hdxx| ponron亚洲| 日本 av在线| 色综合亚洲欧美另类图片| 免费高清在线观看日韩| 又大又爽又粗| 国产亚洲欧美98| 看免费av毛片| 婷婷精品国产亚洲av| 国产av在哪里看| 中文字幕人妻丝袜一区二区| 亚洲中文av在线| 中文字幕人成人乱码亚洲影| 深夜精品福利| 国产欧美日韩一区二区三| cao死你这个sao货| 中出人妻视频一区二区| 国产99久久九九免费精品| 在线观看66精品国产| 久热这里只有精品99| 中文字幕另类日韩欧美亚洲嫩草| 日韩大码丰满熟妇| 久久精品国产99精品国产亚洲性色| 精品高清国产在线一区| 国产成人欧美| 在线永久观看黄色视频| 久久天躁狠狠躁夜夜2o2o| 成人国语在线视频| 怎么达到女性高潮| 精品国产国语对白av| 麻豆成人av在线观看| 婷婷精品国产亚洲av在线| 美女高潮喷水抽搐中文字幕| 视频在线观看一区二区三区| 校园春色视频在线观看| 亚洲欧美日韩高清在线视频| 在线十欧美十亚洲十日本专区| 老司机靠b影院| 亚洲真实伦在线观看| 亚洲av美国av| 亚洲精品中文字幕一二三四区| 91麻豆av在线| 亚洲avbb在线观看| 十分钟在线观看高清视频www| 欧美中文综合在线视频| 亚洲av电影不卡..在线观看| 在线观看日韩欧美| 久久九九热精品免费| www.熟女人妻精品国产| www.精华液| 一区二区三区国产精品乱码| 好看av亚洲va欧美ⅴa在| 不卡一级毛片| 亚洲熟妇中文字幕五十中出| 91国产中文字幕| 母亲3免费完整高清在线观看| 不卡一级毛片| 村上凉子中文字幕在线| 国产精品香港三级国产av潘金莲| 一级片免费观看大全| 中出人妻视频一区二区| 国产成人啪精品午夜网站| 一本一本综合久久| 桃红色精品国产亚洲av| 最近在线观看免费完整版| 国内久久婷婷六月综合欲色啪| 国产亚洲av高清不卡| 草草在线视频免费看| 欧美黑人巨大hd| www.精华液| 国产免费男女视频| 女人高潮潮喷娇喘18禁视频| 哪里可以看免费的av片| 这个男人来自地球电影免费观看| 日本一区二区免费在线视频| 亚洲欧美日韩高清在线视频| 12—13女人毛片做爰片一| 长腿黑丝高跟| 午夜免费激情av| 精品久久久久久久久久免费视频| 精品一区二区三区视频在线观看免费| 国产精品久久久久久精品电影 | 欧美成人性av电影在线观看| 亚洲欧美精品综合久久99| 国产人伦9x9x在线观看| 亚洲国产精品合色在线| 无限看片的www在线观看| 久久精品人妻少妇| 亚洲激情在线av| 母亲3免费完整高清在线观看| 桃色一区二区三区在线观看| 亚洲午夜理论影院| 亚洲成人久久性| 国产又色又爽无遮挡免费看| 一个人免费在线观看的高清视频| 免费在线观看成人毛片| 成人永久免费在线观看视频| 久久国产精品男人的天堂亚洲| 精品久久久久久久毛片微露脸| 长腿黑丝高跟| 俺也久久电影网| 国产精品 欧美亚洲| 精品高清国产在线一区| 国产精品影院久久| 欧美性猛交╳xxx乱大交人| 99精品久久久久人妻精品| 亚洲 欧美一区二区三区| 手机成人av网站| 亚洲av成人不卡在线观看播放网| 变态另类丝袜制服| 成年女人毛片免费观看观看9| 黄色丝袜av网址大全| 侵犯人妻中文字幕一二三四区| 久久精品人妻少妇| 久久香蕉国产精品| 99在线视频只有这里精品首页| 最新美女视频免费是黄的| 亚洲精品在线美女| 国产精品久久久人人做人人爽| 精品久久久久久久末码| 欧美丝袜亚洲另类 | 黄片大片在线免费观看| 欧美人与性动交α欧美精品济南到| 精品久久久久久久久久免费视频| 亚洲色图av天堂| 无遮挡黄片免费观看| 日本a在线网址| 精品欧美一区二区三区在线| 国产伦一二天堂av在线观看| 久久99热这里只有精品18| 别揉我奶头~嗯~啊~动态视频| 黄色毛片三级朝国网站| 97碰自拍视频| 久久人妻福利社区极品人妻图片| 免费看日本二区| 99国产精品一区二区三区| 日韩精品青青久久久久久| 久久久久久大精品| 中国美女看黄片| 成人18禁高潮啪啪吃奶动态图| 天天躁夜夜躁狠狠躁躁| 免费搜索国产男女视频| 观看免费一级毛片| 少妇粗大呻吟视频| 国产三级黄色录像| 国产日本99.免费观看| 成年版毛片免费区| 久久精品aⅴ一区二区三区四区| 国产亚洲av嫩草精品影院| 国产成人av激情在线播放| 中文亚洲av片在线观看爽| АⅤ资源中文在线天堂| 亚洲黑人精品在线| 在线观看午夜福利视频| www.精华液| 9191精品国产免费久久| 九色国产91popny在线| 一级a爱视频在线免费观看| 久久婷婷人人爽人人干人人爱| 免费搜索国产男女视频| 午夜成年电影在线免费观看| 精品电影一区二区在线| 亚洲精品色激情综合| av超薄肉色丝袜交足视频| 可以免费在线观看a视频的电影网站| 国产精品亚洲美女久久久| 久久人人精品亚洲av| 日韩三级视频一区二区三区| 夜夜爽天天搞| 欧洲精品卡2卡3卡4卡5卡区| 中文字幕精品免费在线观看视频| 国产精品久久久人人做人人爽| 国产欧美日韩一区二区精品| 九色国产91popny在线| 国产黄片美女视频| 男女下面进入的视频免费午夜 | 午夜福利免费观看在线| 一个人免费在线观看的高清视频| 高清毛片免费观看视频网站| 1024手机看黄色片| 精品无人区乱码1区二区| 国产激情久久老熟女| 嫩草影院精品99| 免费女性裸体啪啪无遮挡网站| 亚洲欧美一区二区三区黑人| 亚洲五月天丁香| 国产色视频综合| 国产97色在线日韩免费| 高潮久久久久久久久久久不卡| 中文资源天堂在线| 成人精品一区二区免费| 亚洲中文字幕一区二区三区有码在线看 | a在线观看视频网站| 成年人黄色毛片网站| e午夜精品久久久久久久| 级片在线观看| 国产精品一区二区免费欧美| 啦啦啦观看免费观看视频高清| 777久久人妻少妇嫩草av网站| 亚洲真实伦在线观看| 黑丝袜美女国产一区| 最新在线观看一区二区三区| 黑人巨大精品欧美一区二区mp4| 一进一出好大好爽视频| 十八禁人妻一区二区| 亚洲国产欧美网| 亚洲国产看品久久| 午夜精品久久久久久毛片777| 99国产精品99久久久久| 国产午夜福利久久久久久| 视频区欧美日本亚洲| 免费在线观看亚洲国产| 一级毛片精品| 人人妻人人澡欧美一区二区| 国产精品二区激情视频| 欧美人与性动交α欧美精品济南到| 搞女人的毛片| 18禁黄网站禁片午夜丰满| 91老司机精品| 欧美性长视频在线观看| 男女午夜视频在线观看| 午夜福利视频1000在线观看| 色综合婷婷激情| 欧美午夜高清在线| 久久久久九九精品影院| 色av中文字幕| 亚洲成人免费电影在线观看| 最好的美女福利视频网| or卡值多少钱| 免费在线观看成人毛片| av免费在线观看网站| 国产91精品成人一区二区三区| 国产精华一区二区三区| 日日夜夜操网爽| 午夜福利在线在线| 久久中文字幕一级| 午夜福利成人在线免费观看| 欧美一区二区精品小视频在线| 色综合亚洲欧美另类图片| 亚洲成a人片在线一区二区| 国产熟女xx| 免费在线观看影片大全网站| 国内毛片毛片毛片毛片毛片| 国产区一区二久久| 欧美精品啪啪一区二区三区| 亚洲精品粉嫩美女一区| 亚洲人成伊人成综合网2020| 欧美不卡视频在线免费观看 | 欧美 亚洲 国产 日韩一| 国产av一区二区精品久久| 别揉我奶头~嗯~啊~动态视频| 最近最新中文字幕大全电影3 | 老司机靠b影院| 亚洲五月天丁香| 亚洲av成人一区二区三| 香蕉av资源在线| 1024手机看黄色片| 看片在线看免费视频| 中文字幕人成人乱码亚洲影| 在线观看免费日韩欧美大片| 黄色毛片三级朝国网站| 黄色 视频免费看| 国产精品九九99| 成熟少妇高潮喷水视频| 999久久久精品免费观看国产| 听说在线观看完整版免费高清| 一级作爱视频免费观看| 日日爽夜夜爽网站| 99re在线观看精品视频| www.www免费av| 免费观看精品视频网站| 一级a爱片免费观看的视频| 国产精品久久久久久人妻精品电影| 黄色片一级片一级黄色片| 亚洲专区国产一区二区| 久久中文看片网| 在线观看免费午夜福利视频| 久久久久国产精品人妻aⅴ院| 精华霜和精华液先用哪个| 成人亚洲精品一区在线观看| 亚洲成av人片免费观看| 国产日本99.免费观看| 亚洲在线自拍视频| av免费在线观看网站| 侵犯人妻中文字幕一二三四区| av免费在线观看网站| 亚洲av中文字字幕乱码综合 | 男人舔女人的私密视频| 国产一区二区激情短视频| 黑丝袜美女国产一区| 在线观看日韩欧美| 免费观看精品视频网站| 日韩中文字幕欧美一区二区| 成人av一区二区三区在线看| 一a级毛片在线观看| 中文字幕另类日韩欧美亚洲嫩草| 亚洲人成伊人成综合网2020| 看片在线看免费视频| 国产蜜桃级精品一区二区三区| bbb黄色大片| 精品国产超薄肉色丝袜足j| 午夜日韩欧美国产| 亚洲av电影在线进入| 亚洲av中文字字幕乱码综合 | 欧美精品啪啪一区二区三区| 51午夜福利影视在线观看| 国产精品一区二区精品视频观看| 18美女黄网站色大片免费观看| 动漫黄色视频在线观看| 久久九九热精品免费| 18禁观看日本| 美女 人体艺术 gogo| 2021天堂中文幕一二区在线观 | 丁香欧美五月| 久久香蕉激情| 亚洲真实伦在线观看| 成人亚洲精品av一区二区| 国产真人三级小视频在线观看| 黄色丝袜av网址大全| 日韩欧美一区二区三区在线观看| 国产精品电影一区二区三区| 国产一区二区激情短视频| 好看av亚洲va欧美ⅴa在| 国产精品香港三级国产av潘金莲| 欧美久久黑人一区二区| 亚洲片人在线观看| 级片在线观看| 成人免费观看视频高清| 精品第一国产精品| 90打野战视频偷拍视频| 日韩精品中文字幕看吧| 天天添夜夜摸| 国产亚洲精品一区二区www| 中文字幕另类日韩欧美亚洲嫩草| 亚洲专区字幕在线| 日韩高清综合在线| 久久精品人妻少妇| 国产97色在线日韩免费| 久久天堂一区二区三区四区| 亚洲人成网站高清观看| 亚洲性夜色夜夜综合| 国产精品野战在线观看| 成人午夜高清在线视频 | 1024视频免费在线观看| 午夜视频精品福利| 黄色片一级片一级黄色片| 一级a爱片免费观看的视频| 最新在线观看一区二区三区| 国产成人系列免费观看| 制服人妻中文乱码| 久久精品影院6| 成人永久免费在线观看视频| av视频在线观看入口| 精品国产亚洲在线| xxxwww97欧美| 美女午夜性视频免费| 久久久久久久久免费视频了| 亚洲精品国产精品久久久不卡| 老司机深夜福利视频在线观看| 女性生殖器流出的白浆| 成人永久免费在线观看视频| 免费看十八禁软件| 亚洲精品国产区一区二| 夜夜夜夜夜久久久久| 此物有八面人人有两片| √禁漫天堂资源中文www| 51午夜福利影视在线观看| 夜夜看夜夜爽夜夜摸| 国内精品久久久久久久电影| 欧美av亚洲av综合av国产av| 欧美久久黑人一区二区| 极品教师在线免费播放| 岛国在线观看网站| 国产av又大| 村上凉子中文字幕在线| 午夜久久久在线观看| 久久久水蜜桃国产精品网| 丁香六月欧美| 免费搜索国产男女视频| 一进一出抽搐gif免费好疼| 中文字幕精品亚洲无线码一区 | 欧美日本亚洲视频在线播放| 亚洲第一欧美日韩一区二区三区| 亚洲成av片中文字幕在线观看| 午夜久久久久精精品| 嫩草影院精品99| 久久国产精品影院| 好男人在线观看高清免费视频 | 免费在线观看亚洲国产| 99久久久亚洲精品蜜臀av| 别揉我奶头~嗯~啊~动态视频| 人人妻,人人澡人人爽秒播| 亚洲第一电影网av| 国产一卡二卡三卡精品| 国产亚洲精品av在线| 日韩大码丰满熟妇| 一区二区三区高清视频在线| 首页视频小说图片口味搜索| 99国产极品粉嫩在线观看| 欧美国产日韩亚洲一区| 视频区欧美日本亚洲| 精品久久久久久久人妻蜜臀av| 啪啪无遮挡十八禁网站| 欧美激情久久久久久爽电影| 欧美日韩福利视频一区二区| avwww免费| 久久热在线av| 男女之事视频高清在线观看| 岛国在线观看网站| 日韩有码中文字幕| 亚洲国产看品久久| 九色国产91popny在线| 国内毛片毛片毛片毛片毛片| 欧美精品啪啪一区二区三区| av福利片在线| 日韩欧美一区视频在线观看| 久久人妻av系列| 欧美日韩亚洲综合一区二区三区_| 黄网站色视频无遮挡免费观看| 日韩有码中文字幕| 国产蜜桃级精品一区二区三区| 国产亚洲精品综合一区在线观看 | 18禁裸乳无遮挡免费网站照片 | or卡值多少钱| 在线观看免费视频日本深夜| 欧美成人一区二区免费高清观看 | 一本精品99久久精品77| 亚洲精品美女久久久久99蜜臀| 免费在线观看视频国产中文字幕亚洲| 桃红色精品国产亚洲av| 久久久久亚洲av毛片大全| 制服人妻中文乱码| 亚洲av日韩精品久久久久久密| 麻豆成人av在线观看| 久久久久久亚洲精品国产蜜桃av| 国产av一区二区精品久久| 久久精品国产综合久久久| 91国产中文字幕| 欧美又色又爽又黄视频| 午夜久久久久精精品| www.999成人在线观看| 亚洲av五月六月丁香网| 很黄的视频免费| 午夜a级毛片| 看免费av毛片| 免费女性裸体啪啪无遮挡网站| 亚洲欧美精品综合一区二区三区| 亚洲成a人片在线一区二区| 99精品欧美一区二区三区四区| 精品高清国产在线一区| 嫁个100分男人电影在线观看| 国产在线观看jvid| 欧美国产日韩亚洲一区| 日本精品一区二区三区蜜桃| 一级毛片精品| 久久久久久久精品吃奶| 999精品在线视频| 一进一出抽搐动态| 国产又色又爽无遮挡免费看| 亚洲国产精品久久男人天堂| 一二三四社区在线视频社区8| 99精品在免费线老司机午夜| 午夜亚洲福利在线播放| 99久久99久久久精品蜜桃| 亚洲aⅴ乱码一区二区在线播放 | 操出白浆在线播放| 天天躁狠狠躁夜夜躁狠狠躁| 日本三级黄在线观看| 一进一出好大好爽视频| 免费观看精品视频网站| 黄色视频不卡| 国产熟女xx| 国产黄色小视频在线观看| 国产精品免费视频内射| 亚洲精品久久国产高清桃花| 黄色 视频免费看| 在线观看免费午夜福利视频|