• <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 ?

    Molecular engineering of s-triazine and its derivatives applied in surface modification strategy for enhancing photoelectric performance of all-inorganic perovskites

    2022-03-14 09:30:46YifeiYueShengnanLiuNingZhangZhongminSuDongxiaZhu
    Chinese Chemical Letters 2022年1期

    Yifei Yue,Shengnan Liu,Ning Zhang,Zhongmin Su,Dongxia Zhu

    Key Laboratory of Nanobiosensing and Nanobioanalysis at Universities of Jilin Province,Department of Chemistry,Northeast Normal University,Changchun 130024,China

    ABSTRACT We develop the effective modification strategy based on molecular engineering of s-triazine and its derivatives to improve the photoelectric performance of all-inorganic perovskites(AIP)for the first time.The surface modification strategy with cyanuric acid successfully increases the PLQY of AIP from 40.55%to 88.15%,and significantly enhances the current of the AIP film under 3 V by almost 20-fold(from 4.44 mA to 81.20 mA).This work has proven the effectiveness of improving the photoelectric performances of AIP via s-triazine and its derivatives and also suggested the potential risks of reducing the photoelectric performance of AIP due to inappropriate substituents in conjugated organic ligands.

    Keywords:All-inorganic perovskites Surface modification s-Triazine Substituents Photoelectric performance

    Since the first example of all-inorganic perovskites(AIP)nanomaterials were reported in 2015[1],researchers have prepared a series of AIP with excellent photoelectric performances[2–5].Although the photoluminescence quantum yield(PLQY)of AIP has reached near-unity[6],the low charge-transport property caused by non-conjugated organic ligands still makes a certain gap between AIP and traditional semiconductor quantum dots(QDs)[7]and organic luminescent materials[8],which seriously hindered the development level of AIP in many application field[9].The ligand exchange reactions in polar solvents were used to improve the charge-transport property of traditional semiconductor QDs[10],which was useless for AIP with low stability in the polar solvents[11].Therefore,researching effective methods for improving the charge-transport property of the AIP is imperative to promote the application of AIP.

    In recent years,researchers have actively explored methods to improve the charge-transport property of AIP and have made certain progress.In the early studies,less polar solvents and inorganic ligands have been applied in the preparation process of CsPbBr3QDs to decrease the density of oleic acid(OA)and oleylamine(OLA)[12,13].In order to avoid the loss of PLQY caused by the decrease of OA and OLA density during the purification process,short-chain organic ligands have been used to instead of longchain organic ligands to modify the surface of AIP to increase the charge-transport property[14,15].In follow-up researches,the organic ligands with conjugated structure have been used to further increase charge-transport property of AIPviathe intermolecularπ-πinteraction to avoid the insulation caused by aliphatic carbon chains[16,17].Compared with the phenethylammonium iodide,the aniline iodide without a carbon chain between the benzene ring and the substituent has shown more excellent modification property[18,19],which indicates the substituent in conjugated organic ligands will also play an important role on the surface modification effect.Although a series of derivatives ofs-triazine have shown outstanding charge-transport property in the application of perovskite solar cell[20,21]and organic light-emitting diodes[22,23],it is ignored based on them to modify AIP luminescent nanomaterials.Therefore,the surface modification strategy withs-triazine is expected to improve luminescence performance and charge-transport property of AIP simultaneously.

    Here,s-triazine(TZ)and its derivatives(cyanuric acid named as CA and trithiocyanuric acid named as TA)were applied in surface modification strategy for enhancing photoelectric performance of AIP for the first time.The PLQY of AIP was increased to 88.15% and the current under 3V of the AIP film was enhanced from 4.44 mA to 81.20 mA with the modification of cyanuric acid(CA).Under the influence of hydroxyl group,CA has shown better modification ability than TZ.However,the effect of TA on the photoelectric performance of the AIP is negative for the sulfhydryl group will introduce extra free Pb2+to cause more surface defects.The completely different surface modification results of CA and TA has shown the effectiveness of the improving the photoelectric performances and also indicated the potential risk of reducing PLQY of AIP either based on conjugated organic ligands at the meanwhile.

    Fig.1.The structures of AIP before and after surface modification strategy:CsPbBr3-0,CsPbBr3-TA,CsPbBr3-TZ and CsPbBr3-CA.

    The AIP without the modification with 3N ligands was named as CsPbBr3-0.The AIP modified by TA,TZ and CA were named as CsPbBr3-TA,CsPbBr3-TZ and CsPbBr3-CA,respectively,the whole of which was named as CsPbBr3-3N.The CsPbBr3-0 and CsPbBr3-3N were are prepared with hot-injection method and the dosages of surface ligands were listed in Tables S1-S3(Supporting information).The structures of AIP before and after modified with 3N ligands were shown in Fig.1.

    The solid powder X-ray diffraction(XRD)measurements were used to study the effect of three conjugated organic ligands on the host lattice of AIP.The obvious diffraction peaks can be found in the XRD patterns of the three organic ligands(Fig.S2 in Supporting information),indicating that AIP show goodish crystallization ability due to large polarity chemical bonds and the strong intermolecularπ-πinteraction happened in the 3N ligands.(Table S4 in Supporting information).

    Before modified with 3N ligands,the characteristic diffraction peaks of CsPbBr3around 15°,22° and 30° can be observed in the XRD pattern of CsPbBr3-0,and the diffraction peaks between 30° and 31° are double peaks(Fig.S3 in Supporting information),which means the lattice structure of CsPbBr3-0 is orthogonal[24].With the increasing the contents of TA,the double-peak diffraction peak around 30° moves to the low-angle region indicating that TA only induces the crystalline interplanar spacing to increase(Fig.S3).Compared with CsPbBr3-TA,the diffraction peaks located around 30° move to the low-angle region with a smaller amplitude in the XRD patterns of CsPbBr3-TZ(Fig.S4 in Supporting information).Especially when the dosage of TZ is increased to more than 0.09 mmol,the double diffraction peaks around 30° gradually become a single diffraction peak,indicating that TZ will induce AIP to form cubic crystal lattice(Fig.S4)[25].The diffraction peaks of CA can be observed in the XRD patterns of CsPbBr3-CA(Figs.2a and b),which indicates that CA will form crystalline layer on the crystal surface because of intermolecular hydrogen bonds and stronger intermolecularπ-πinteraction according to the theoretical calculation results(Table S4)[26].Correspondingly,the position change of the peak around 30° in the XRD patterns of CsPbBr3-CA is the smallest among the three CsPbBr3-3N(Figs.2a and b).When modified with 0.06 mmol CA,the diffraction peak around 30° becomes a single peak(Figs.2a and b),meaning that CsPbBr3-CA has cubic crystal lattice.Thus,different substituents make these ligands have different influence on the host lattice.

    Fig.2.(a)Full and(b)enlarged(from 30° to 32°)solid XRD patterns of CsPbBr3-0 and CsPbBr3-CA.(c)Full and(d)enlarged(from 480 cm?1 to 600 cm?1)FT-IR spectra of CsPbBr3-0 and CsPbBr3-CA.

    The compositions of the organic ligands in CsPbBr3-3N were analyzed on the basis of fourier transform infrared spectroscopy(FT-IR)measurements.The characteristic peak of C-S bond at 1120 cm?1can be observed in the FT-IR spectrum of TA,which also can be found in that of CsPbBr3-TA(Fig.S5 in Supporting information).Moreover,there is a new peak at 1220 cm?1in the FT-IR spectra of CsPbBr3-TA(Fig.S5).The intensity of the peak at 1220 cm?1increases as the amount of TA increases,while the intensity of the peak at 1120 cm?1decreases(Fig.S5),suggesting that the C-S bond in TA changes during the modification process with TA.In the FT-IR spectra of CsPbBr3-TZ,the characteristic peak of TZ located in the fingerprint region of 520 cm?1can be directly observed,which moves to a low wavenumber region,indicating that the vibration of the chemical bond is limited after TZ adsorbing on the host lattice(Fig.S6 in Supporting information).Due to the tautomer of CA,there are characteristic peaks of hydroxyl group and carbonyl group in the FT-IR spectrum of CA,which are also found in the FT-IR spectra of CsPbBr3-CA without any change(Fig.2c).The characteristic peak of CA located in the fingerprint area appears in the FT-IR spectra of CsPbBr3-CA and changes to a certain extent(Figs.2c and d),meaning that CA interacts with the host lattice through the triazine ring instead of hydroxyl group or carbonyl group.

    1H nuclear magnetic resonance(1H NMR)measurements were performed on CsPbBr3-0 and CsPbBr3-3N to obtain the chemical environment of the protons in these materials(Fig.S7 in Supporting information).The chemical environment of the proton hydrogen in CsPbBr3-TA is as same as CsPbBr3-0(Fig.S7),indicating that the sulfhydryl group in TA will lose protons during the reaction,which changes the vibration state of the C-S bond.Compared with CsPbBr3-0,the proton signal of TZ can be clearly found in the1H NMR spectrum of CsPbBr3-TZ(Fig.S7),which further suggests TZ have adsorbed on the host lattice.Meanwhile,the proton signals of the tautomers of CA in Fig.S7 suggest CA adsorb on the host lattice by triazine ring which is consisted with the analysis of FT-IR.

    The effect of 3N ligands on the nanotopography of AIP was studied through transmission electron microscope(TEM)images.Before the modification with 3N ligands,CsPbBr3-0 shows various nanotopography in the TEM image,such as nanowires and nanocubes(Fig.3a).Many regular nanospheres can be found in Figs.3b and c,showing TA and TZ are beneficial to form the uniform nanotopography.The nanotopography of CsPbBr3-CA appears as a large cross-linked network(Fig.3d),due to the crystalline layer on the surface of the host lattice.Therefore,CA exhibit significantly different influence on the nanotopography due to hydroxyl group.

    Fig.3.TEM images(scale bar is 50 nm)of(a)CsPbBr3-0,(b)CsPbBr3-TA 0.09 mmol,(c)CsPbBr3-TZ 0.09 mmol and(d)CsPbBr3-CA 0.09 mmol.

    The elemental composition on the surface of the AIP was obtained by energy dispersive spectroscopy(EDS)measurements.As the amount of TA increases,the ratio of Br:Pb decreased from 3.26 to 3.07,2.84 and 1.37(Table S6 in Supporting information).The proton-losing sulfhydryl groups of TA will adsorb a large amount of free Pb2+[27],which will increase surface defects of AIP to reduce PLQY[28].The ratios of Br:Pb on the surface of CsPbBr3-TZ and CsPbBr3-CA are increased to 3.95,4.27,4.25,4.09,3.98 and 4.14,respectively(Tables S7 and S8 in Supporting information),which will enhance PLQY of AIP by decreasing surface defects[29].Therefore,the surface structure and defect states of AIP have shown obviously opposite modification results under the influence of the 3N ligands with different substituents.

    The absorption and photoluminescence(PL)spectra of AIP show different changes due to the different substituents on triazine ring.In the absorption spectra,maximum absorption wavelength of TA is the largest and that of CA is the smallest(Fig.S8 in Supporting information),which is consistent with the results of theoretical calculation(Table S5 in Supporting information).When the dosage of TA increases to 0.09 and 0.12 mmol,an absorption peak of 315 nm appears in the absorption spectra of CsPbBr3-TA,which is also present in the absorption spectra of CsPbBr3-TZ and CsPbBr3-CA,indicating that triazine ring will induce quasi-2D structure in the AIP(Fig.S8)[30].It is worth noting that the absorption peak at 315 nm is unconspicuous in the absorption spectra of CsPbBr3-TA 0.09 mmol and CsPbBr3-TA 0.12 mmol,which is even barely visible in the absorption curve of CsPbBr3-TA 0.06 mmol,indicating that the modification ability of the triazine ring in TA is weakened due to the sulfydryl group(Fig.S8a).The emission peak of CsPbBr3-TA occurs blue-shift with the increase of ligand content,while the emission peaks of CsPbBr3-TZ and CsPbBr3-CA show red-shift first and then blue-shift(Figs.S9a,c,e in Supporting information).

    Fig.4.(a)PLQY of CsPbBr3-0 and CsPbBr3-3N 0.09 mmol solid powder(λex=390 nm).(b)Electricity of CsPbBr3-0 and CsPbBr3-3N 0.09 mmol films under 3 V.

    The PLQYs and fluorescence decay curves were obtained to study the effects of 3N ligands on the exciton recombination process of AIP(Figs.S9b,d,f in Supporting information),with which the radiation transition rate(kr)and the non-radiative transition rate(knr)of AIP were calculated.Theknrof CsPbBr3-TA is larger than CsPbBr3-0(Table S9 in Supporting information),indicating that the defect density on the surface of CsPbBr3-TA is greater than that of CsPbBr3-0,which is caused by excessive free Pb2+on the surface.These changes result in that the PLQY of CsPbBr3-TA(1.24%-33.35%)is lower than CsPbBr3-0(40.55%).When the amount of TA is 0.06 mmol and 0.12 mmol,thekrof CsPbBr3-TA is smaller than that of CsPbBr3-0,while thekrof CsPbBr3-TA 0.09 mmol is larger than that of CsPbBr3-0(Table S9),for which the PLQY of CsPbBr3-TA 0.09 mmol(33.35%)is the highest among CsPbBr3-TA.Theknrof CsPbBr3-TZ is smaller than CsPbBr3-0(Table S10),indicating that TZ can well reduce the defect density on the surface of AIP.When the amount of TZ increases to 0.12 mmol,knrof the corresponding material began to increase(Table S10 in Supporting information),indicating that the excessive TZ at this time causes the interplanar spacing of the host lattice to change too much,which would increase the defect density on the surface.Similar to CsPbBr3-TA,thekrof CsPbBr3-TZ shows a trend of first decreasing,then increasing and then decreasing with the increase of TZ dosage(Table S10).As for CsPbBr3-TZ 0.09 mmol,thekrreaches the maximum andknris at the minimum,achieving the highest PLQY among CsPbBr3-TZ(85.47%).After modifying the host lattice with CA,theknrof AIP decreases with the amount of CA increasing(Table S11 in Supporting information),which means that CA can significantly reduce the surface defect density of AIP.Different from CsPbBr3-TA and CsPbBr3-TZ,theknrof CsPbBr3-CA 0.12 mmol is less than CsPbBr3-CA 0.09 mmol(Table S11).Combined with the XRD analysis results,CA has little effect on the interplanar spacing of the host lattice,which can be inferred that 0.12 mmol of CA will not cause a large interplanar change and increase surface defects.Thekrof CsPbBr3-CA shows the same trend as CsPbBr3-TA and CsPbBr3-TZ(Table S11).Correspondingly,CsPbBr3-CA 0.09 mmol exhibits the largest PLQY(88.15%).Since the three organic ligands all contain triazine ring,it can be inferred that an appropriate amount of triazine ring can effectively increase thekrof AIP.These three triazine ring-based organic ligands exhibit different influence on PLQY of AIP due to the different substituents(Fig.4a).

    Since thekrof CsPbBr3-TA 0.09 mmol,CsPbBr3-TZ 0.09 mmol,and CsPbBr3-CA 0.09 mmol are all higher than CsPbBr3-0,variable temperature fluorescence measurements were performed on these four materials to further explore the reasons.In Fig.S10(Supporting information),CsPbBr3-0 shows four emission peaks at low temperature,while CsPbBr3-TA 0.09 mmol,CsPbBr3-TZ 0.09 mmol and CsPbBr3-CA 0.09 mmol all maintained single emission peak(Fig.S10),indicating that the nanotopography of CsPbBr3-3N is more uniform,which coincides with the TEM images.In Fig.S10,the emission intensity of CsPbBr3-0 begins to decrease rapidly at 115 K as the temperature rises,while this temperature is increased to 230 K(CsPbBr3-TA 0.09 mmol),150 K(CsPbBr3-TZ 0.09 mmol)and 150 K(CsPbBr3-CA 0.09 mmol)after the surface modification with 3N ligands.This result means that all of the 3N ligands can increase the exciton binding energy of AIP to increase thekrof AIPs[31].Although CsPbBr3-TA 0.09 mmol has shown the largest exciton binding energy,due to the influence of surface defects caused by sulfhydryl group,thekrof CsPbBr3-TA 0.09 mmol is smaller than that of CsPbBr3-CA 0.09 mmol.Therefore,the surface state of the AIP can be tuned through controlling the amount of ligand and the type of substituent,so as to realize the optimization on the luminescence performance of AIP.

    In the discussion about luminescence performance,CsPbBr3-TA 0.09 mmol,CsPbBr3-TZ 0.09 mmol and CsPbBr3-CA 0.09 mmol have shown better luminescence performance(Fig.4a).Therefore,the content of OA and OLA in these three materials and CsPbBr3-0 and the charge-transport property of the material films were tested respectively.The contents of organic ligands in these four materials were obtained through DTG measurements(Table S12 in Supporting information).The mass percentage of OA and OLA in the CsPbBr3-0 totals 27.7%,which is significantly reduced in CsPbBr3-3N,suggesting that the 3N ligands can significantly reduce the density of OA and OLA on the surface of AIP.The charge-transport property of these four kinds of AIP films were measured through a device with a structure of ITO/AIP/Al.The current-voltage curve in the film under the forward voltage is shown in Fig.S11(Supporting information).The currents in CsPbBr3-0,CsPbBr3-TA 0.09 mmol,CsPbBr3-TZ 0.09 mmol and CsPbBr3-CA 0.09 mmol films gradually increase under the same voltage(Fig.4b),which proves that the organic ligands containing the triazine ring exhibit two notable advantages for the great enhancement on the charge-transport property of AIP:strong intermolecularπ-πinteraction and lowering the density of OA and OLA on the surface of AIP[32].Among the CsPbBr3-3N films,CsPbBr3-TA 0.09 mmol shows the worst chargetransport property,because the more surface defects caused by TA will reduce the charge-transport property of AIP[33].The CsPbBr3-CA 0.09 mmol shows the best charge-transport property due to the stronger modification ability and intermolecularπ-πinteraction of CA inferred from the results of theoretical calculation.Therefore,3N ligands can greatly improve the charge-transport property of AIP,and CA shows the best the optimization effect.

    We successfully improve the photoelectric performance of AIPviachanging the substituents to optimize the modification ability of conjugated organic ligand.According to the results of XRD,FT-IR,PL and other measurements,it can be proved that the surface modification strategy withs-triazine can effectively improve the luminescence performance and charge transport performance of AIP through the triazine ring structure.The addition of appropriate groups(such as hydroxyl)to the triazine ring structure can significantly enhance the modification effect of organic ligands.Meanwhile,the inappropriate substituents(such as sulfhydry)will introduce additional surface defects on the surface of AIP and reduce the modification effect of organic ligands.This study leads researchers to notice the great influence of molecular design strategy on the modification effect of organic ligand in surface modification strategy of AIP.

    Declaration of competing interest

    The authors declare no conflict of interest.

    Acknowledgments

    This work was funded by National Natural Science Foundation of China(No.52073045),the Key Scientific and Technological Project of Jilin Province(No.20190701010GH),and the Development and Reform Commission of Jilin Province(No.2020C035-5).D.Zhu is grateful for the support from the Key Laboratory of Nanobiosensing and Nanobioanalysis at the Universities of Jilin Province.The authors acknowledge the support from the Jilin Provincial Department of Education.

    Supplementary materials

    Supplementary material associated with this article can be found,in the online version,at doi:10.1016/j.cclet.2021.06.066.

    av黄色大香蕉| 日韩中文字幕欧美一区二区| 国产伦精品一区二区三区视频9| 亚洲狠狠婷婷综合久久图片| 亚洲人与动物交配视频| 18+在线观看网站| 91久久精品电影网| 床上黄色一级片| 免费高清视频大片| 婷婷精品国产亚洲av在线| 在线免费观看的www视频| 欧美在线一区亚洲| 国内久久婷婷六月综合欲色啪| 少妇熟女aⅴ在线视频| 亚洲精品亚洲一区二区| 久久久久久大精品| 色视频www国产| 欧美高清成人免费视频www| .国产精品久久| 久久精品国产自在天天线| 日韩欧美免费精品| 99久国产av精品| 国产精品亚洲美女久久久| 亚洲精品亚洲一区二区| 在线观看美女被高潮喷水网站| 在线免费观看不下载黄p国产 | 亚洲精品粉嫩美女一区| 国产美女午夜福利| 韩国av一区二区三区四区| 午夜福利高清视频| a级毛片a级免费在线| 精品人妻熟女av久视频| 国产精品野战在线观看| 日日啪夜夜撸| 99九九线精品视频在线观看视频| 免费看av在线观看网站| 婷婷亚洲欧美| 国产91精品成人一区二区三区| 久久午夜福利片| 亚洲人成网站在线播| 看免费成人av毛片| 精品一区二区免费观看| 久久国内精品自在自线图片| 啦啦啦韩国在线观看视频| 国产一区二区三区视频了| 在线免费观看的www视频| 国产精华一区二区三区| 国产精品野战在线观看| 色在线成人网| 欧美在线一区亚洲| 十八禁国产超污无遮挡网站| 99视频精品全部免费 在线| 久久99热这里只有精品18| 欧美成人a在线观看| 精品99又大又爽又粗少妇毛片 | 日本一二三区视频观看| 99热精品在线国产| av在线蜜桃| 欧美精品国产亚洲| 亚洲四区av| 国产成人a区在线观看| av.在线天堂| 亚洲一级一片aⅴ在线观看| 亚洲精品影视一区二区三区av| 亚洲美女搞黄在线观看 | 亚洲美女视频黄频| 毛片女人毛片| 免费一级毛片在线播放高清视频| 精品人妻1区二区| 欧美性猛交╳xxx乱大交人| 97超级碰碰碰精品色视频在线观看| av专区在线播放| 日韩欧美 国产精品| 亚洲精品粉嫩美女一区| 欧美3d第一页| 波野结衣二区三区在线| 十八禁网站免费在线| 亚洲欧美清纯卡通| 成人欧美大片| 国产精品无大码| 免费看美女性在线毛片视频| 欧洲精品卡2卡3卡4卡5卡区| 国产精品1区2区在线观看.| 久久99热这里只有精品18| 日韩欧美精品免费久久| av专区在线播放| 久久欧美精品欧美久久欧美| 亚洲av熟女| 内地一区二区视频在线| 免费观看在线日韩| 久久精品影院6| 精品人妻熟女av久视频| 欧美绝顶高潮抽搐喷水| 他把我摸到了高潮在线观看| 一进一出抽搐动态| 国产精品乱码一区二三区的特点| 最新中文字幕久久久久| 久久午夜亚洲精品久久| 日韩一区二区视频免费看| 波多野结衣高清无吗| 极品教师在线免费播放| 欧美国产日韩亚洲一区| 国产免费一级a男人的天堂| 女生性感内裤真人,穿戴方法视频| 一级黄片播放器| 国产精品99久久久久久久久| www.色视频.com| 午夜老司机福利剧场| 国产在线精品亚洲第一网站| 国内精品美女久久久久久| 国产一区二区在线av高清观看| 韩国av在线不卡| 特级一级黄色大片| 国产精品免费一区二区三区在线| 欧美xxxx性猛交bbbb| 韩国av一区二区三区四区| 18禁黄网站禁片免费观看直播| 国产精品嫩草影院av在线观看 | 他把我摸到了高潮在线观看| 最近在线观看免费完整版| 欧美潮喷喷水| 亚洲美女黄片视频| 嫩草影院入口| 国产伦精品一区二区三区四那| 日本五十路高清| 91在线精品国自产拍蜜月| 亚洲美女搞黄在线观看 | 长腿黑丝高跟| 性欧美人与动物交配| 少妇高潮的动态图| 哪里可以看免费的av片| 成年女人毛片免费观看观看9| 亚洲精品一卡2卡三卡4卡5卡| 国产精品国产三级国产av玫瑰| 成人性生交大片免费视频hd| 国产伦一二天堂av在线观看| 高清日韩中文字幕在线| 51国产日韩欧美| 欧美人与善性xxx| 成人国产麻豆网| 国产亚洲av嫩草精品影院| 欧美潮喷喷水| 日韩精品有码人妻一区| 18禁黄网站禁片午夜丰满| 国产精品99久久久久久久久| 国产成年人精品一区二区| 51国产日韩欧美| 亚洲va日本ⅴa欧美va伊人久久| 国产伦精品一区二区三区视频9| 久久久久国内视频| 欧美日本视频| 日本色播在线视频| or卡值多少钱| 欧美另类亚洲清纯唯美| 成人一区二区视频在线观看| 久久久久久九九精品二区国产| 国产一区二区激情短视频| 欧美xxxx性猛交bbbb| 国产免费男女视频| 免费av毛片视频| 禁无遮挡网站| 91在线观看av| 亚洲精品一区av在线观看| 欧美日韩乱码在线| 九九爱精品视频在线观看| 日韩大尺度精品在线看网址| 亚洲乱码一区二区免费版| 国产黄色小视频在线观看| 女的被弄到高潮叫床怎么办 | 噜噜噜噜噜久久久久久91| bbb黄色大片| 免费在线观看日本一区| 亚洲国产精品sss在线观看| 日本a在线网址| 亚洲美女搞黄在线观看 | 成人国产一区最新在线观看| 日韩av在线大香蕉| 成人综合一区亚洲| 亚洲真实伦在线观看| 国产伦人伦偷精品视频| av在线老鸭窝| 亚洲精品一区av在线观看| 亚洲欧美日韩卡通动漫| 啦啦啦韩国在线观看视频| av天堂在线播放| 校园人妻丝袜中文字幕| 日本一本二区三区精品| 一级a爱片免费观看的视频| 一个人观看的视频www高清免费观看| 久久久精品大字幕| 久久这里只有精品中国| 99热这里只有是精品在线观看| 又紧又爽又黄一区二区| 国产黄色小视频在线观看| 国产 一区 欧美 日韩| 嫩草影视91久久| 丝袜美腿在线中文| 尾随美女入室| 黄色配什么色好看| 日韩人妻高清精品专区| 久久精品综合一区二区三区| 熟女人妻精品中文字幕| 小蜜桃在线观看免费完整版高清| 一进一出抽搐gif免费好疼| 变态另类丝袜制服| 中亚洲国语对白在线视频| 亚洲精品乱码久久久v下载方式| 亚洲人成网站在线播放欧美日韩| 精品久久久久久久久亚洲 | 色尼玛亚洲综合影院| 免费av不卡在线播放| 国产精品免费一区二区三区在线| 毛片女人毛片| 日日摸夜夜添夜夜添小说| 在线观看免费视频日本深夜| 亚洲精品日韩av片在线观看| 我要看日韩黄色一级片| 亚洲人与动物交配视频| 日日摸夜夜添夜夜添小说| 三级国产精品欧美在线观看| 久久久久久久久久黄片| 国产精华一区二区三区| 国产 一区 欧美 日韩| 国产精品亚洲一级av第二区| 国产精品av视频在线免费观看| 亚洲七黄色美女视频| 国产单亲对白刺激| 国产精品人妻久久久久久| av中文乱码字幕在线| 日日干狠狠操夜夜爽| 免费观看精品视频网站| 国产午夜精品久久久久久一区二区三区 | 亚州av有码| 干丝袜人妻中文字幕| 国产极品精品免费视频能看的| 国产黄色小视频在线观看| 欧美最黄视频在线播放免费| 色吧在线观看| 亚洲精品乱码久久久v下载方式| 亚洲av中文av极速乱 | 嫩草影视91久久| 久久久久国内视频| 国产黄片美女视频| 日本a在线网址| 99久久精品一区二区三区| 久久精品国产亚洲av香蕉五月| 一进一出抽搐动态| 国产免费一级a男人的天堂| 99久久无色码亚洲精品果冻| 国产免费男女视频| 黄色视频,在线免费观看| 99热这里只有是精品50| 国产精品久久久久久av不卡| 在线播放无遮挡| 日本精品一区二区三区蜜桃| 国产av一区在线观看免费| 亚洲乱码一区二区免费版| 1024手机看黄色片| 亚洲成人免费电影在线观看| 欧美黑人巨大hd| 亚洲精华国产精华液的使用体验 | 午夜福利欧美成人| 日本黄色片子视频| 99国产极品粉嫩在线观看| 国产亚洲精品久久久com| 成人国产综合亚洲| 观看美女的网站| 日韩大尺度精品在线看网址| 亚州av有码| 亚洲avbb在线观看| 免费在线观看影片大全网站| 日本免费a在线| 99精品在免费线老司机午夜| 亚洲国产精品sss在线观看| 亚洲aⅴ乱码一区二区在线播放| 色综合婷婷激情| 亚洲国产欧洲综合997久久,| 真实男女啪啪啪动态图| 日韩欧美一区二区三区在线观看| 色av中文字幕| 亚洲国产精品sss在线观看| 一进一出抽搐动态| 国产爱豆传媒在线观看| 精品欧美国产一区二区三| 欧美最新免费一区二区三区| 色播亚洲综合网| 国产伦在线观看视频一区| 亚洲精品粉嫩美女一区| 精品国内亚洲2022精品成人| 亚洲国产欧洲综合997久久,| 精品久久久久久久久久免费视频| 我的女老师完整版在线观看| 中文字幕人妻熟人妻熟丝袜美| 3wmmmm亚洲av在线观看| 极品教师在线视频| 91av网一区二区| 韩国av在线不卡| 成人毛片a级毛片在线播放| 中国美女看黄片| 成人高潮视频无遮挡免费网站| 舔av片在线| 日日夜夜操网爽| 亚洲av免费在线观看| 日韩欧美在线二视频| 搡老岳熟女国产| 99热6这里只有精品| 免费在线观看影片大全网站| 久9热在线精品视频| 在线观看免费视频日本深夜| 一边摸一边抽搐一进一小说| 国产精品98久久久久久宅男小说| 久久亚洲真实| 亚洲专区国产一区二区| 91在线精品国自产拍蜜月| 欧美日韩国产亚洲二区| 一级毛片久久久久久久久女| 特级一级黄色大片| 嫩草影院新地址| 韩国av一区二区三区四区| 亚洲精品国产成人久久av| 成人一区二区视频在线观看| 床上黄色一级片| 成人美女网站在线观看视频| 88av欧美| 亚洲三级黄色毛片| 变态另类丝袜制服| 免费一级毛片在线播放高清视频| 国产精品日韩av在线免费观看| 久久久精品大字幕| 哪里可以看免费的av片| 日韩大尺度精品在线看网址| 国产黄a三级三级三级人| 欧美一级a爱片免费观看看| 久久久久久伊人网av| 亚洲精品乱码久久久v下载方式| 欧美日韩精品成人综合77777| 啦啦啦啦在线视频资源| 少妇人妻一区二区三区视频| 精品日产1卡2卡| 村上凉子中文字幕在线| 老司机午夜福利在线观看视频| 亚洲精品一区av在线观看| 中文字幕精品亚洲无线码一区| 两个人的视频大全免费| 午夜精品久久久久久毛片777| 国产极品精品免费视频能看的| 男人的好看免费观看在线视频| 在线观看免费视频日本深夜| 99久久精品国产国产毛片| 欧美日韩综合久久久久久 | 天天一区二区日本电影三级| 日本爱情动作片www.在线观看 | www日本黄色视频网| 免费看av在线观看网站| 一级a爱片免费观看的视频| 欧美中文日本在线观看视频| 97人妻精品一区二区三区麻豆| 夜夜夜夜夜久久久久| 国产av在哪里看| 国产中年淑女户外野战色| 久久精品人妻少妇| 中文字幕精品亚洲无线码一区| 欧美+亚洲+日韩+国产| 狂野欧美白嫩少妇大欣赏| ponron亚洲| 午夜爱爱视频在线播放| 久久精品人妻少妇| 夜夜夜夜夜久久久久| 国产三级在线视频| 国产精品久久久久久久久免| www日本黄色视频网| 欧美成人免费av一区二区三区| 欧美日韩精品成人综合77777| 老司机福利观看| 色噜噜av男人的天堂激情| 老司机福利观看| 国产不卡一卡二| 欧美日韩亚洲国产一区二区在线观看| 男人舔女人下体高潮全视频| 99久久成人亚洲精品观看| 日日撸夜夜添| 啦啦啦观看免费观看视频高清| 免费高清视频大片| 色综合婷婷激情| 欧美性猛交╳xxx乱大交人| 国产午夜精品论理片| 免费大片18禁| 国产精品国产高清国产av| 免费搜索国产男女视频| 国语自产精品视频在线第100页| 一个人观看的视频www高清免费观看| 免费无遮挡裸体视频| 国产精品久久久久久av不卡| 一区二区三区激情视频| 好男人在线观看高清免费视频| 人妻夜夜爽99麻豆av| 能在线免费观看的黄片| av天堂在线播放| 欧美3d第一页| 国产高清激情床上av| 精品久久久久久久久久久久久| 丰满人妻一区二区三区视频av| av在线老鸭窝| 国产一区二区激情短视频| 国产精品人妻久久久久久| 欧美一区二区亚洲| 欧美日韩瑟瑟在线播放| 成人无遮挡网站| 一区二区三区激情视频| 可以在线观看的亚洲视频| 亚洲精品在线观看二区| 中出人妻视频一区二区| 99久久精品热视频| 国产成人a区在线观看| 九色成人免费人妻av| 免费一级毛片在线播放高清视频| 欧美性猛交╳xxx乱大交人| 两性午夜刺激爽爽歪歪视频在线观看| 免费人成视频x8x8入口观看| 99视频精品全部免费 在线| 男人和女人高潮做爰伦理| 久久热精品热| 男人狂女人下面高潮的视频| 婷婷六月久久综合丁香| 国产色婷婷99| 听说在线观看完整版免费高清| 日韩国内少妇激情av| 毛片一级片免费看久久久久 | 精品免费久久久久久久清纯| 欧美最新免费一区二区三区| 麻豆国产av国片精品| 日韩精品青青久久久久久| 色视频www国产| 国产不卡一卡二| 久久精品国产亚洲av天美| 一a级毛片在线观看| 在线观看午夜福利视频| 亚洲av熟女| 免费观看精品视频网站| 3wmmmm亚洲av在线观看| 性色avwww在线观看| 亚洲,欧美,日韩| 国产av不卡久久| 国产探花在线观看一区二区| 九九久久精品国产亚洲av麻豆| 女人被狂操c到高潮| ponron亚洲| 一本一本综合久久| 国产亚洲精品久久久久久毛片| 欧美性感艳星| 国产激情偷乱视频一区二区| 美女高潮喷水抽搐中文字幕| 亚洲美女搞黄在线观看 | 精品人妻视频免费看| 在线免费观看不下载黄p国产 | 国产真实乱freesex| 国产亚洲精品久久久久久毛片| 深爱激情五月婷婷| 一个人观看的视频www高清免费观看| 色av中文字幕| 97人妻精品一区二区三区麻豆| 美女高潮的动态| 国产精品久久久久久亚洲av鲁大| 熟女人妻精品中文字幕| 免费在线观看影片大全网站| 国内精品宾馆在线| 亚洲经典国产精华液单| 天天躁日日操中文字幕| 能在线免费观看的黄片| 男人舔奶头视频| 美女高潮的动态| 国产毛片a区久久久久| 一夜夜www| 国产免费男女视频| 成人午夜高清在线视频| 熟妇人妻久久中文字幕3abv| 中文字幕熟女人妻在线| 99精品在免费线老司机午夜| 国产精品精品国产色婷婷| 白带黄色成豆腐渣| 真人一进一出gif抽搐免费| 99国产极品粉嫩在线观看| 亚洲久久久久久中文字幕| 亚洲av免费在线观看| 亚洲午夜理论影院| 午夜福利在线观看吧| 国产精品综合久久久久久久免费| 一级av片app| 国产精品一及| 中文字幕av在线有码专区| 天美传媒精品一区二区| 日本黄色视频三级网站网址| 97超级碰碰碰精品色视频在线观看| 搡女人真爽免费视频火全软件 | 老女人水多毛片| 女生性感内裤真人,穿戴方法视频| 一个人看视频在线观看www免费| 日韩高清综合在线| 久久欧美精品欧美久久欧美| 直男gayav资源| 麻豆国产97在线/欧美| 天天一区二区日本电影三级| 午夜精品在线福利| 少妇人妻一区二区三区视频| 国产精品一区二区免费欧美| 少妇裸体淫交视频免费看高清| 国产视频一区二区在线看| 国产中年淑女户外野战色| 亚洲美女视频黄频| 精品久久久久久久人妻蜜臀av| 丝袜美腿在线中文| 国产爱豆传媒在线观看| 亚洲男人的天堂狠狠| 天堂√8在线中文| 内射极品少妇av片p| 国产精华一区二区三区| 国产精品无大码| 九色国产91popny在线| 黄色视频,在线免费观看| 又紧又爽又黄一区二区| 国产日本99.免费观看| 久久亚洲精品不卡| 亚洲av中文字字幕乱码综合| 亚洲五月天丁香| 欧美+亚洲+日韩+国产| 久久精品国产亚洲av天美| 国产精品日韩av在线免费观看| 亚洲av五月六月丁香网| 可以在线观看的亚洲视频| 一区福利在线观看| 成人精品一区二区免费| 亚洲精华国产精华精| 精品人妻偷拍中文字幕| 精品久久久久久成人av| 欧美一区二区国产精品久久精品| 国产乱人伦免费视频| 国产精品一区www在线观看 | 成人一区二区视频在线观看| 69av精品久久久久久| 欧美一区二区精品小视频在线| 亚洲人成网站在线播| 国国产精品蜜臀av免费| 欧美最新免费一区二区三区| aaaaa片日本免费| 免费电影在线观看免费观看| 亚洲,欧美,日韩| 亚洲最大成人手机在线| 五月伊人婷婷丁香| 国产精品野战在线观看| 国产精品久久视频播放| 久久欧美精品欧美久久欧美| 一本精品99久久精品77| 少妇裸体淫交视频免费看高清| 午夜福利在线观看免费完整高清在 | 淫秽高清视频在线观看| 99视频精品全部免费 在线| 成年免费大片在线观看| 国产精品一区二区三区四区久久| 亚洲国产精品合色在线| 国产麻豆成人av免费视频| 九九久久精品国产亚洲av麻豆| 亚洲精华国产精华液的使用体验 | 日韩av在线大香蕉| 日韩一本色道免费dvd| 直男gayav资源| 18禁在线播放成人免费| 三级国产精品欧美在线观看| 亚洲人成网站在线播| 淫秽高清视频在线观看| 成人特级黄色片久久久久久久| 美女高潮的动态| 长腿黑丝高跟| 婷婷精品国产亚洲av| 久久久久性生活片| 国产精品免费一区二区三区在线| 国产探花极品一区二区| 熟女人妻精品中文字幕| 久久久久久久久大av| 亚洲,欧美,日韩| 99精品久久久久人妻精品| 国产精品av视频在线免费观看| 免费av观看视频| 性插视频无遮挡在线免费观看| 亚洲成人久久性| 直男gayav资源| 免费大片18禁| 91久久精品电影网| av黄色大香蕉| 亚洲av第一区精品v没综合| 22中文网久久字幕| 乱码一卡2卡4卡精品| 最近中文字幕高清免费大全6 | 午夜精品在线福利| 国内揄拍国产精品人妻在线| 国产精品不卡视频一区二区| 久久久色成人| 久久精品国产亚洲av香蕉五月| 国产成人一区二区在线| 午夜精品久久久久久毛片777| 99久久精品热视频| 特级一级黄色大片| 国产美女午夜福利| 免费不卡的大黄色大毛片视频在线观看 | 日本黄色视频三级网站网址| 亚洲av不卡在线观看| 露出奶头的视频| 亚洲一区二区三区色噜噜| 亚洲不卡免费看| 一级毛片久久久久久久久女| 欧美一区二区精品小视频在线| 天堂影院成人在线观看| 校园人妻丝袜中文字幕| 成人国产一区最新在线观看| 国产在线精品亚洲第一网站| 少妇猛男粗大的猛烈进出视频 |