In recent years, the Laser display has drawn wide attention due to its large color gamut and high brightness. However, the poor uniformity of color and illumination induced by the monochromatic laser has become an urgent technical problem to solve. In this work, we designed a new optical illumination frame, added a Gaussian 2° diffuser at the diffuse 1 position, expanded and shimmed the laser beam, and uniquely added an achromatic half-wave plate in front of the two red array lasers. To verify the improvement of this optical illumination frame on the illumination and color uniformity, we built a laser illumination system by using a Hitachi NUMM31 model 4*7 array laser, 639nm, 643nm 2*7 red array laser, 525nm 1*7 green array laser, and 465nm 1*7 blue array laser. Moreover, the simulation of color uniformity was conducted by lighttools. The result of color uniformity is Δx=0.08 and Δy=0.01. As a result, the color uniformity of our new optical illumination frame below 0.015 was achieved, while the color uniformity of Hisense products is 0.025. This newly developed optical illumination frame has the high potential to provide a facile pathway to realize high color and illumination uniformity by using diffusers and an achromatic half-wave plate.
As a new generation of display technology, Laser displays a wide range of color gamut, high brightness, and other characteristics. However, as a highly coherent light source, laser speckle will be generated by the interference phenomenon of the reflected light or transmitted light of different surface elements after the incident on the surface of the object, which will seriously reduce the quality of the display image. Therefore, the suppression of laser speckle and the reduction of speckle contrast are always important problems in laser display technology. Here, we presented a speckle suppression scheme suitable for projector optical systems. Speckle suppression by spectral broadening and speckle suppression by superposition of multiple independent and unrelated speckle patterns are included in the scheme. Then, the feasibility of the scheme was verified by simulation. On this basis, the projector system was built. The speckle suppression scheme was added, and the effect of the scheme on speckle contrast was verified by actual measurement, and the speckle contrast was successfully reduced from 0.129 to 0.041, which was difficult for human eyes to distinguish.
KEYWORDS: Absorption, Solar cells, Luminescence, Organic photovoltaics, Binary data, Photovoltaics, Doping, Energy transfer, Active optics, Solar energy
In this study, we report the ternary organic solar cells by doping a thermally activated delayed fluorescence (TADF) material (4 s ,6 s )-2,4,5,6-tetra( 9H -carbazol-9-yl) isophthalonitrile (4CzIPN) in the binary poly(3-hexylthiophene) (P3HT) :[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) blends. Given the complementary absorption with P3HT, 4CzIPN was doped into (P3HT:PC71BM)-based binary blends, and ternary OSCs were developed, The ternary OSCs with 1.0 wt% of 4CzIPN displayed better phase separation of active layer, thus leading to an impressive efficiency of 3.94 % with open-circuit voltage of 0.54 V, short-circuit density of 11.58 mA/cm-2 and fill factor of 63.32%.
Fluorescence/phosphorescence hybrid white organic light-emitting devices (WOLEDs) with non-doped emitting layers are constructed based on blue, green and red dyes. The simplified emitting layers (EMLs) are fabricated with structure of Blue/Red/Blue/Green hybrid emitting layers consisting of an ultrathin non-doped green phosphorescence layer employing Tris(2-phenylpyridine)iridium (Ir(ppy)3), an ultrathin non-doped red phosphorescence layer using Tris(1-(4-hexylphenyl)-isoquinolinato-C2,N)iridium(III) (Ir(h-piq)3), and double non-doped blue thermally activated delayed fluorescence (TADF) layers using 9,9-dimethyl-9,10-dihydroacridine- diphenylsulfone (DMAC-DPS). A white OLED are fabricated with relatively stable electroluminescence spectra of white emission achieves maximum luminance, maximum current efficiency, power efficiency and external quantum efficiency of 21596cd/m2, 8.45 cd/A, 11.57 lm/W and 6%, respectively. The result shows a slight variation of Commission International de l’Eclairage (CIE) coordinates (0.026, 0.051) at a luminance ranging from 32 cd/m2 to 2728 cd/m2. It suggests that the bipolar charge carrier transport property of DMAC-DPS contributes to control of exciton recombination in the emissive regions and balance white emission.
KEYWORDS: Solar cells, Solar energy, Polymers, Organic photovoltaics, Doping, Molecules, Resonance energy transfer, Photovoltaics, Absorption, Molecular energy transfer
In this work, we fabricated the ternary bulk hetero junction (BHJ) polymer solar cells (PSCs) by doping a phosphorescent small molecule bis[2-(4-tertbutylphenyl)benzothiazolato-N,C2′] iridium(acetylacetonate)[(tbt)2Ir(acac)] into the conventional active layer of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). After doping (tbt)2Ir(acac), the short circuit current and fill factor are simultaneously enhanced compared with binary device and the power conversion efficiency (PCE) of P3HT:PC71BM based ternary devices is improved from 2.99% to 4.14%. More excellent photovoltaic performance of ternary PSCs is mainly attributed to enhanced charge transportation by appropriate energy cascade alignment and enhanced exciton harvesting by Foerster resonance energy transfer from (tbt)2Ir(acac) to P3HT.
Low-voltage pentacene-based organic thin film transistors (OTFTs) are fabricated with solution-process hafnium oxide (HfO2) as gate dielectric layer. The dielectric high-k HfO2 film was deposited from the sol-gel solution prepared by dissolving HfCl4(98%, Sigma-Aldrich) in ethanol at a proper concentration. We have investigated the effects of the insulating layer on device. As a result, the device with only HfO2 gate dielectric exhibited a good performance with a threshold voltage of -0.88 V, a sub-threshold swing of 1.12 V/dec, and a high field-effect mobility of 1×10-3 cm2/Vs. After employing a very thin PMMA film onto HfO2, the performance of the devices with bilayer dielectrics shows a great improvement. The mobility of these OTFTs can be further boost up to 1.2×10-2 cm2/Vs, and the sub-threshold swing reduced to 0.77 V/dec and the drain current on/off ratio increased almost 7 times. The PMMA insulator buffer layer can also effectively reduce gate leakage current. The results demonstrate that an appropriate polymer buffer layer is a favorable way to improve the performance of the OTFTs with good electrical stability.
White organic light-emitting devices (WOLEDs) with a novel direct hole-injection structure based on the hole transport capability of bis[2-(4-tert-butylphenyl) benzothiazolato-N,C2'] iridium(acetylacetonate) [(t-bt)2I-r(acac)] were fabricated. By inserting an electron-blocking layer, we successfully manipulated electron transport and achieved white light emission. A maximum luminance of 26020 cd/m2, a maximum current efficiency of 22.37 cd/A and a maximum power efficiency of 18.99 lm/W were obtained. This novel structure can significantly simplify the production processes of WOLEDs and deserves further investigation.
Phosphorescent materials are crucial to improve the luminescence and efficiency of organic light emitting diodes, because its internal quantum efficiency can almost up to 100%. So the studying of optical and electrical properties of phosphorescent materials is propitious to the further development of phosphorescent OLED. Phosphorescent materials were generally doped into different host materials as emitting components, not only played an important role in emitting light but also had a great influence on carrier transport properties. (t-bt)2Ir(acac) was a common yellow phosphorescent material. The optical and electrical properties of the blue DPVBi-based devices, adding (t-bt)2Ir(acac) in different position, have studied. The results showed (t-bt)2Ir(acac) has remarkable hole-trapping ability. Especially the ultrathin structure device, compared to the device without (t-bt)2Ir(acac), had increased the luminance by about 60%, and the efficiency by about 97%.
Polymer:fullerene bulk-heterojunction hybrid solar cells with the structure indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate)(PEDOT:PSS)/poly(3-hexylthiophene)(P3HT):[6,6]-phe nylC61-butyric(PCBM)/bathophenanthroline(Bphen)/Ag were fabricated. In this paper, the electrical characteristics of bulk heterojunction organic solar cells with various thickness of P3HT:PCBM as the active layer and Bphen as an exciton-blocking layer(EBL) were studied. The results showed that the P3HT:PCBM layer at about 110nm perform best, the open circuit voltage(Voc) , short circuit current(Jsc) and the power conversion efficiency(PCE) reach to 0.57V, 10.82mA/cm2, 2.50%, respectively; then when Bphen was 1nm, Voc is 0.56V, Jsc is 12.64mA/cm2, PCE reach the maximum 3.30%.
To improve the low efficiency and color impurity in red fluorescent top-emitting organic light-emitting devices (OLEDs), a yellow phosphorescent iridium complex of bis[2-(4-tertbutylphenyl)benzothiazolato-N,C2'] iridium (acetylacetonate) [(t-bt)2Ir(acac)] was introduced to a red device with a fluorescent material 3-(dicyanomethylene)-5,5-dimethyl-1-(4-dimethylamino-styryl)cyclohexene (DCDDC), respectively. By adjusting the concentration of DCDDC dye, the luminescence spectra and electrics characteristics of various devices were investigated. The results showed that the performance of the fluorescent-phosphor-sensitized devices were significant improved comparing to the traditional red fluorescent devices. The function of phosphor-sensitizer in energy transfer mechanism was analyzed. The affects of phosphor-sensitizer in these co-doped red OLED were discussed.
The S-shaped J-V curves in planar heterojunction organic solar cells (OSCs) using triplet material bis[2-(4-
tertbutylphenyl)benzothi azolato-N, C2,] iridium (acetylacetonate) [(t-bt)2Ir(acac)] as donor and C60 as acceptor were diminished by substrate heating during film deposition of (t-bt)2Ir(acac) layer. Mobility measurements showed that the disappearance of S-kinks was attributed to the significant increase of hole mobility in (t-bt)2Ir(acac) by heating the substrate during evaporation and thus the decrease of mobility mismatch between electrons and holes, leading to the improvement of fill factor (FF). Moreover, the photocurrent density (Jph) of heated device was remarkable enhanced and showed decreased space charge limited (SCL) effect due to the balanced charge transport and the increase of charge collection efficiency (ηCC). As a result, by heating the substrate at 70 ℃, a power conversion efficiency (PCE) of 1.63 % was achieved compared to 1.37 % for the unheated device. Using this method, organic solar cells based on triplet materials allow thicker active layer thickness for light absorption without introducing much fill factor loss.
Double heterojunction organic solar cells (OSCs) using poly (3, 4-ethylenedioxythiophene): poly (4-styrenesulfonic acid) (PEDOT: PSS) as an anode modification layer and fullerene (C60) as an acceptor layer were fabricated and characterized. The results showed that short-circuit current density (JSC), open-circuit voltage (VOC), fill factor (FF) and power conversion efficiency (PCE) increase apparently by using the anode modification layer although it may block the light absorption. A maximum power conversion efficiency of 1.02 % has been achieved by employing 90 nm thick poly (2-methoxy, 5-(2’-ethylhexyloxy)-1, 4-phenylene vinylene) (MEH-PPV) as an electron donating layer.
A 1.8-in. high-resolution passive matrix OLED (PMOLED) display panel has been successfully developed. We design the structure of full color PMOLED device. We pattern the device on a 128×3×160 pixel area, 384 row ITO anodes and 160 column cathode separators on ITO glass developed by us through photolithograph process. We have successfully fabricated the 1.8-in. 128×160 full color passive OLED display panel through our SUNICEL PLUS 200 OLED systems. The structure of OLED is a double-hetero structure. It has the device structure of ITO/2TNATA/NPB/ Alq3+C545T/Alq3/LiF/Al for green, ITO/2TNATA/ NPB/Alq3+Rubrene+DCJTB/ Alq3/LiF/Al for red, ITO/2TNATA/
NPB/EB43+TBPE/Alq3/LiF/Al for blue. The PMOLED display panel has full color emission with a resolution of 128×160, and the brightness of 200 cd/m2, as well as the lifetime of 5000 hours. The open aperture ratio of each pixel is 45%.
ITO (Indium tin oxide) film has been widely used as transparent electrode for organic light-emitting diodes (OLEDs).
Higher conductibility and transparency, smoother surface morphology and higher work function are indispensable for the
fabrication of high performance OLEDs, especially for transparent and double-side devices. Therefore, it is necessary to
deposit ITO films at low temperature to protect the organic films of OLED from damaging during fabrication process. In
this work a novel transparent electrode ITO/Ag/ITO was introduced to the OLED device. This kind of transparent
electrode was used to reduce the sheet resistance of electrode and raise the performance of OLED device. By theoretical
simulation, the optimum film thickness of three organic layers was obtained. ITO and Ag films were prepared by DC
magnetron sputtering at room temperature. The transparent electrode with low sheet resistance of 6.3 Ω/sq and high
transmittance of 87% at 550 nm was achieved. OLED consisted of this multilayer film was developed. The relationship
between the thickness of Ag film and photoelectric performance of multilayer films was also discussed.
A novel kind of multilayer blue organic light-emitting diode (OLED) was developed via vacuum thermal deposition method. Host and dopant materials were co-deposited to fabricate as an emissive layer (EML) simultaneously. The film thickness of each layer was controlled with a quartz crystal microbalance. Typical device structure was ITO/CuPc (20 nm)/NPB (60 nm)/B-host (40 nm) : dopant (X wt%)/Alq3 (20 nm)/LiF (1 nm)/Al (100 nm), where X% stands for the doping concentration in the EML of OLED. The weight ratio was changed from 1% to 4%. Optical and electronic performance including current, bias voltage, brightness, efficiency and spectra of the devices varied with doping concentration was characterized. The results showed the turn-on voltage of the device with 1% doping concentration was lower than that of others, which was only 3.5 V. When X wt% was 3%, the brightness of the device reached to be 9,500 cdm-2 at a driving voltage of 20 V with blue emission spectrum peak 472 nm corresponding to the CIE coordinates of x=0.147, y=0.215 and a maximum luminance efficiency of 2.92 lmW-1. The brightness of the device increased linearly with the bias voltage ranging from 3.5 to 52 V. The results also showed that the doping OLED was very steady under high driving voltage at ambient atmosphere.
In this study, four kinds of organic light-emitting diodes were developed using vacuum deposition technique. The typical multilayer structures of OLED are ITO / CuPc(200 Å) / α-NPD(600 Å) / Alq3(400 Å) : C545T(X%) / Alq3(200 Å) /LiF(10 Å) / Al(1000 Å) , X% is the doping consistence in Emitter Layer of OLED. The value is change from 1% to 4%. In this letter, the optical and electronic performance including brightness, efficiency, spectrum etc. was change with the doping consistence. When X% is 1%, the steady voltage of device start working is lower than other structures, only 2.5V. When X% is 3%, the brightness of the device was measured to be 10,500cd times m-2 at the drive voltage 20V, CIE coordinates x=0.331, y=0.625 and maximum luminous efficiency 6.72 lm•W-1 at 5 V. When X% is 4%, the green emission spectrum peak is 550nm, almost reach 555nm (standard green spectrum peak).
A full color 2.2" passive matrix organic light-emitting diodes (OLEDs) with 128 (RGB) * 160 pixels was developed. The display features that driving circuit can transform 18 bits gray-scale data from a PC to the OLED panel via a DVI channel. The size of the pixel was 240μm×240μm, while that of mono sub-pixel is 190μm×45μm. The lifetime of panel was estimated over 5000h because of the use of dual-scan driving technology, and the power consumption of the display was 300mw about when the average luminance of panel reach 40cd/m2.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.