A model of universal single layer organic solar cells in metal-insulator-metal (MIM) representation involving field-depen-dent carrier mobility is set up. The current-voltage characteristics as well as the distributio...A model of universal single layer organic solar cells in metal-insulator-metal (MIM) representation involving field-depen-dent carrier mobility is set up. The current-voltage characteristics as well as the distribution of electron density,hole density and recombination rate on a set of parameters are simulated. Subsequently,the dependences of the short-circuit current density (Jsc) and open-circuit voltage (Voc) on the electron and hole zero-field mobility,excitation generation rate,energy gap,as well as electron-hole pair distance in an excitation are investigated. It is demonstrated that the enhancement of either the electron mobility or the hole mobility can contribute to the increase of Jsc in the devices. The increase of the hole mobility can lead to the improvement of both Jsc and Voc,and the simultaneous increase of the electron mobility and hole mobility will greatly elevate Jsc but maintain a steady Voc. Additionally,all the increases of the excitation generation rate,energy gap and electron-hole pair distance are beneficial to both the remarkable increases of Jsc and Voc of the devices.展开更多
The carrier mobility of Si material can be enhanced under strain,and the stress magnitude can be measured by the Raman spectrum.In this paper,we aim to study the penetration depths into biaxially-strained Si materials...The carrier mobility of Si material can be enhanced under strain,and the stress magnitude can be measured by the Raman spectrum.In this paper,we aim to study the penetration depths into biaxially-strained Si materials at various Raman excitation wavelengths and the stress model corresponding to Raman spectrum in biaxially-strained Si.The experimental results show that it is best to use 325 nm excitation to measure the material stress in the top strained Si layer,and that one must pay attention to the distortion of the buffer layers on measuring results while 514 nm excitation is also measurable.Moreover,we established the stress model for Raman spectrum of biaxially-strained Si based on the Secular equation.One can obtain the stress magnitude in biaxially-strained Si by the model,as long as the results of the Raman spectrum are given.Our quantitative results can provide valuable references for stress analysis on strained materials.展开更多
Multilayer gallium and aluminum doped ZnO （GZO/AZO） films were fabricated by alternative deposition of Ga-doped zinc oxide（GZO） and Al-doped zinc oxide（AZO） thin film by using pulsed laser deposition（PLD） proc...Multilayer gallium and aluminum doped ZnO （GZO/AZO） films were fabricated by alternative deposition of Ga-doped zinc oxide（GZO） and Al-doped zinc oxide（AZO） thin film by using pulsed laser deposition（PLD） process. The electrical and optical properties of these GZO/AZO thin films were investigated and compared with those of GZO and AZO thin films. The GZO/AZO （1：1） thin film deposited at 400 ~C shows the electrical resistivity of 4.18 x 10 4 ~.cm, an electron concentration of 7.5 x 1020/cm3, and carrier mobility of 25.4 cm2/（V.s）. The optical transmittances of GZO/AZO thin films are over 85%. The optical band gap energy of GZO/AZO thin films linearly decreases with increasing the AI ratio.展开更多
Polymer photovoltaic devices based on poly (2- methoxy-5-(2′ -ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH- PPV) with three weight-average molecular weights (Mw) have been fabricated with the device structure of ITO/...Polymer photovoltaic devices based on poly (2- methoxy-5-(2′ -ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH- PPV) with three weight-average molecular weights (Mw) have been fabricated with the device structure of ITO/PEDOT/ MEH-PPV/Ca/Ag, and the effect of the molecular weight on photovoltaic properties has been investigated. The experi- mental results show that the high molecular weight of MEH- PPV leads to low series resistance (Rs) and high short-circuit current. The low molecular weight of MEH-PPV leads to high shunt resistance (Rsh) and high open-circuit voltage. When the molecular weight is 6×105, the highest power con- version efficiency was observed.展开更多
By utilizing poly（3-hexylthiophene） （P3HT） polymer nanowires with diameters of -15 nm as the vertical channel material, a polymer nanowire vertical transistor has been demonstrated for the first time. The P3HT nan...By utilizing poly（3-hexylthiophene） （P3HT） polymer nanowires with diameters of -15 nm as the vertical channel material, a polymer nanowire vertical transistor has been demonstrated for the first time. The P3HT nanowires were characterized by absorption spectroscopy and scanning electron microscopy. A saturated output current was created by increasing the thickness of the polymer layers between the electrodes through several spin-coating cycles of the polymer nanowires prepared in a marginal solvent. The carrier mobility was also increased through utilization of polymer nanowires with strong interchain interactions. By introducing a small hole injection barrier between the emitter and semiconducting polymer, an on/off current ratio of 1,500 was obtained. The operating voltage is less than 2 V.展开更多
We report a small molecule host of 4,4(-N,N)-dicarbazole-biphenyl(CBP) doped with 8% tris(2-phenylpyridine) iridium(Irppy3) for use in efficient green phosphorescent organic light-emitting devices(PHOLEDs) combined wi...We report a small molecule host of 4,4(-N,N)-dicarbazole-biphenyl(CBP) doped with 8% tris(2-phenylpyridine) iridium(Irppy3) for use in efficient green phosphorescent organic light-emitting devices(PHOLEDs) combined with different electron transport layers of Alq and BAlq. The PHOLEDs exhibit maximum current efficiency and power efficiency of 19.8 cd/A and 6.21 lm/W, respectively. The high performance of such PHOLEDs is attributed to the better electron mobile ability of BAlq and sub-monolayer quinacridone(QAD) as carrier trapping layer and equal charge carrier mobilities of hole and electron to form the broad carrier recombination zone in the emitting layer, which can 1reduce the triplet-triplet annihilation and improve the efficiency of the device.展开更多
Since 1994, the vertical directional solidification （VDS） technique is employed for the growths of bulk crystals-without the seed, without contact to the ampoule wall, without coating and without external pressure, ...Since 1994, the vertical directional solidification （VDS） technique is employed for the growths of bulk crystals-without the seed, without contact to the ampoule wall, without coating and without external pressure, which leads to the detached growth. Growth velocities ranged from 3 mm/h to 10 mm/h, and rotation rates 10-20 rpm have been used. Ingots, 10-20 mm diameter and 60-65 mm length, have been grown with the conical ampoule geometry and these ingots have shown symmetric detachment. Crystals grown under such conditions showed the relatively low dislocation density and the highest carrier mobility,/tn = 5.9 x 104 cm2＂Vl-sl than the crystal grown ever. For the detached crystals, the dislocation density is 104 cm＂2 in conical region, and reached less than 103 cm-2 in the direction of the growth, when the ingots are not in contact with the ampoule wall. Experiments for indium-antimonide （InSb） growth have shown that the 80% growth environments have detachment, 15% entrapped in conical region and 5% attached.展开更多
Graphene,comprising a monolayer of carbon atoms packed into a two-dimensional(2D)honeycomb lattice,has received great attention due to its special properties,including massless Dirac fermions,linear dispersion relatio...Graphene,comprising a monolayer of carbon atoms packed into a two-dimensional(2D)honeycomb lattice,has received great attention due to its special properties,including massless Dirac fermions,linear dispersion relation near the Dirac cones,high carrier mobility,emerged quantum confinements,and gate-tunable optical transitions.Nevertheless,both the fundamental and application-oriented graphene investigations are commonly concerned with the graphene 2D plane.展开更多
基金the State Talent-Cultivation Fund for Basic Science of China (No.J0630313)
文摘A model of universal single layer organic solar cells in metal-insulator-metal (MIM) representation involving field-depen-dent carrier mobility is set up. The current-voltage characteristics as well as the distribution of electron density,hole density and recombination rate on a set of parameters are simulated. Subsequently,the dependences of the short-circuit current density (Jsc) and open-circuit voltage (Voc) on the electron and hole zero-field mobility,excitation generation rate,energy gap,as well as electron-hole pair distance in an excitation are investigated. It is demonstrated that the enhancement of either the electron mobility or the hole mobility can contribute to the increase of Jsc in the devices. The increase of the hole mobility can lead to the improvement of both Jsc and Voc,and the simultaneous increase of the electron mobility and hole mobility will greatly elevate Jsc but maintain a steady Voc. Additionally,all the increases of the excitation generation rate,energy gap and electron-hole pair distance are beneficial to both the remarkable increases of Jsc and Voc of the devices.
基金supported by the Research Fund for the Doctoral Program of Higher Education of China(Grant No.JY0300122503)the NLAIC Research Fund(Grant No.P140c090303110c0904)
文摘The carrier mobility of Si material can be enhanced under strain,and the stress magnitude can be measured by the Raman spectrum.In this paper,we aim to study the penetration depths into biaxially-strained Si materials at various Raman excitation wavelengths and the stress model corresponding to Raman spectrum in biaxially-strained Si.The experimental results show that it is best to use 325 nm excitation to measure the material stress in the top strained Si layer,and that one must pay attention to the distortion of the buffer layers on measuring results while 514 nm excitation is also measurable.Moreover,we established the stress model for Raman spectrum of biaxially-strained Si based on the Secular equation.One can obtain the stress magnitude in biaxially-strained Si by the model,as long as the results of the Raman spectrum are given.Our quantitative results can provide valuable references for stress analysis on strained materials.
基金supported by the Yeungnam University Research Grants in 2009
文摘Multilayer gallium and aluminum doped ZnO （GZO/AZO） films were fabricated by alternative deposition of Ga-doped zinc oxide（GZO） and Al-doped zinc oxide（AZO） thin film by using pulsed laser deposition（PLD） process. The electrical and optical properties of these GZO/AZO thin films were investigated and compared with those of GZO and AZO thin films. The GZO/AZO （1：1） thin film deposited at 400 ~C shows the electrical resistivity of 4.18 x 10 4 ~.cm, an electron concentration of 7.5 x 1020/cm3, and carrier mobility of 25.4 cm2/（V.s）. The optical transmittances of GZO/AZO thin films are over 85%. The optical band gap energy of GZO/AZO thin films linearly decreases with increasing the AI ratio.
文摘Polymer photovoltaic devices based on poly (2- methoxy-5-(2′ -ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH- PPV) with three weight-average molecular weights (Mw) have been fabricated with the device structure of ITO/PEDOT/ MEH-PPV/Ca/Ag, and the effect of the molecular weight on photovoltaic properties has been investigated. The experi- mental results show that the high molecular weight of MEH- PPV leads to low series resistance (Rs) and high short-circuit current. The low molecular weight of MEH-PPV leads to high shunt resistance (Rsh) and high open-circuit voltage. When the molecular weight is 6×105, the highest power con- version efficiency was observed.
文摘By utilizing poly（3-hexylthiophene） （P3HT） polymer nanowires with diameters of -15 nm as the vertical channel material, a polymer nanowire vertical transistor has been demonstrated for the first time. The P3HT nanowires were characterized by absorption spectroscopy and scanning electron microscopy. A saturated output current was created by increasing the thickness of the polymer layers between the electrodes through several spin-coating cycles of the polymer nanowires prepared in a marginal solvent. The carrier mobility was also increased through utilization of polymer nanowires with strong interchain interactions. By introducing a small hole injection barrier between the emitter and semiconducting polymer, an on/off current ratio of 1,500 was obtained. The operating voltage is less than 2 V.
基金supported by the Major Project of Science and Technology Office of Fujian Province of China(No.2014H0042)the Natural Science Foundation of Fujian Province of China(No.2015J01664)+1 种基金the Project of Science and Technology Research of Quanzhou in Fujian Province of China(Nos.2013Z125 and 2014Z137)the 2016 Annual National or Ministries Preparatory Research Foundation Project in Quanzhou Normal University(No.2016YYKJ21)
文摘We report a small molecule host of 4,4(-N,N)-dicarbazole-biphenyl(CBP) doped with 8% tris(2-phenylpyridine) iridium(Irppy3) for use in efficient green phosphorescent organic light-emitting devices(PHOLEDs) combined with different electron transport layers of Alq and BAlq. The PHOLEDs exhibit maximum current efficiency and power efficiency of 19.8 cd/A and 6.21 lm/W, respectively. The high performance of such PHOLEDs is attributed to the better electron mobile ability of BAlq and sub-monolayer quinacridone(QAD) as carrier trapping layer and equal charge carrier mobilities of hole and electron to form the broad carrier recombination zone in the emitting layer, which can 1reduce the triplet-triplet annihilation and improve the efficiency of the device.
文摘Since 1994, the vertical directional solidification （VDS） technique is employed for the growths of bulk crystals-without the seed, without contact to the ampoule wall, without coating and without external pressure, which leads to the detached growth. Growth velocities ranged from 3 mm/h to 10 mm/h, and rotation rates 10-20 rpm have been used. Ingots, 10-20 mm diameter and 60-65 mm length, have been grown with the conical ampoule geometry and these ingots have shown symmetric detachment. Crystals grown under such conditions showed the relatively low dislocation density and the highest carrier mobility,/tn = 5.9 x 104 cm2＂Vl-sl than the crystal grown ever. For the detached crystals, the dislocation density is 104 cm＂2 in conical region, and reached less than 103 cm-2 in the direction of the growth, when the ingots are not in contact with the ampoule wall. Experiments for indium-antimonide （InSb） growth have shown that the 80% growth environments have detachment, 15% entrapped in conical region and 5% attached.
文摘Graphene,comprising a monolayer of carbon atoms packed into a two-dimensional(2D)honeycomb lattice,has received great attention due to its special properties,including massless Dirac fermions,linear dispersion relation near the Dirac cones,high carrier mobility,emerged quantum confinements,and gate-tunable optical transitions.Nevertheless,both the fundamental and application-oriented graphene investigations are commonly concerned with the graphene 2D plane.
