A method is discussed for using neural networks to control optical tweezers. Neural-net outputs are combined with scaling and tiling to generate 480X480-pixel control patterns for a spatial light modulator (SLM). The SLM can be combined in various ways with a microscope to create movable tweezers traps with controllable profiles. The neural nets are intended to respond to scattered light from carbon and silicon carbide nanotube sensors. The nanotube sensors are to be held by the traps for manipulation and calibration. Scaling and tiling allow the 100X100-pixel maximum resolution of the neural-net software to be applied in stages to exploit the full 480X480-pixel resolution of the SLM. One of these stages is intended to create sensitive null detectors for detecting variations in the scattered light from the nanotube sensors.
{"title":"Neural network for image-to-image control of optical tweezers","authors":"A. Decker, R. Anderson, K. E. Weiland, S. Wrbanek","doi":"10.1117/12.559564","DOIUrl":"https://doi.org/10.1117/12.559564","url":null,"abstract":"A method is discussed for using neural networks to control optical tweezers. Neural-net outputs are combined with scaling and tiling to generate 480X480-pixel control patterns for a spatial light modulator (SLM). The SLM can be combined in various ways with a microscope to create movable tweezers traps with controllable profiles. The neural nets are intended to respond to scattered light from carbon and silicon carbide nanotube sensors. The nanotube sensors are to be held by the traps for manipulation and calibration. Scaling and tiling allow the 100X100-pixel maximum resolution of the neural-net software to be applied in stages to exploit the full 480X480-pixel resolution of the SLM. One of these stages is intended to create sensitive null detectors for detecting variations in the scattered light from the nanotube sensors.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122518178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Laser systems are finding a home in many military applications - such as Space Situational Awareness, imaging and weapons systems. With an increasing focus on programs that entail atmospheric propagations, there is a need for a cost effective method of performing laboratory proof-of-concept demonstrations. The use of one SLM (single phase screen) to model atmospheric effects has been investigated previously with promising results. However, some effects cannot be captured with a single SLM. This paper focuses on the addition of a second SLM and quantifying the results. Multiple screens will allow the user to independently control the Fried parameter, the isoplanatic angle, and Rytov Variance. The research is comprised of simulation and experiment. The simulation demonstrates the ability to accurately model atmospheric effects with two phase screens. Based on the simulation, a hardware implementation was tested in the lab. The results of this research show promise, however some issues remain. This thesis describes the experimental set-up and results based on measurement of phase and intensity of the propagated field. It was noted that while analytic results are replicated in simulation, similar results in the lab were difficult to achieve.
{"title":"Atmospheric turbulence simulation using liquid crystal spatial light modulators","authors":"J. Phillips, M. Goda, Jason D. Schmidt","doi":"10.1117/12.620407","DOIUrl":"https://doi.org/10.1117/12.620407","url":null,"abstract":"Laser systems are finding a home in many military applications - such as Space Situational Awareness, imaging and weapons systems. With an increasing focus on programs that entail atmospheric propagations, there is a need for a cost effective method of performing laboratory proof-of-concept demonstrations. The use of one SLM (single phase screen) to model atmospheric effects has been investigated previously with promising results. However, some effects cannot be captured with a single SLM. This paper focuses on the addition of a second SLM and quantifying the results. Multiple screens will allow the user to independently control the Fried parameter, the isoplanatic angle, and Rytov Variance. The research is comprised of simulation and experiment. The simulation demonstrates the ability to accurately model atmospheric effects with two phase screens. Based on the simulation, a hardware implementation was tested in the lab. The results of this research show promise, however some issues remain. This thesis describes the experimental set-up and results based on measurement of phase and intensity of the propagated field. It was noted that while analytic results are replicated in simulation, similar results in the lab were difficult to achieve.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127547090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Test and evaluation of laser warning devices is important due to the increased use of laser devices in aerial applications. This research consists of an atmospheric aberrating system to enable in-lab testing of various detectors and sensors. This system employs laser light at 632.8nm from a Helium-Neon source and a spatial light modulator (SLM) to cause phase changes using a birefringent liquid crystal material. Measuring outgoing radiation from the SLM using a CCD targetboard and Shack-Hartmann wavefront sensor reveals an acceptable resemblance of system output to expected atmospheric theory. Over three turbulence scenarios, an error analysis reveals that turbulence data matches theory. A wave optics computer simulation is created analogous to the lab-bench design. Phase data, intensity data, and a computer simulation affirm lab-bench results so that the aberrating SLM system can be operated confidently.
{"title":"Atmospheric simulation using a liquid crystal wavefront-controlling device","authors":"M. Brooks, M. Goda","doi":"10.1117/12.562447","DOIUrl":"https://doi.org/10.1117/12.562447","url":null,"abstract":"Test and evaluation of laser warning devices is important due to the increased use of laser devices in aerial applications. This research consists of an atmospheric aberrating system to enable in-lab testing of various detectors and sensors. This system employs laser light at 632.8nm from a Helium-Neon source and a spatial light modulator (SLM) to cause phase changes using a birefringent liquid crystal material. Measuring outgoing radiation from the SLM using a CCD targetboard and Shack-Hartmann wavefront sensor reveals an acceptable resemblance of system output to expected atmospheric theory. Over three turbulence scenarios, an error analysis reveals that turbulence data matches theory. A wave optics computer simulation is created analogous to the lab-bench design. Phase data, intensity data, and a computer simulation affirm lab-bench results so that the aberrating SLM system can be operated confidently.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130137622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Light exposure regulates several circadian functions in normal humans including the sleep-wake cycle. Individuals with Alzheimer’s Disease (AD) often do not have regular patterns of activity and rest, but, rather, experience random periods of sleep and agitation during both day and night. Bright light during the day and darkness at night has been shown to consolidate activity periods during the day and rest periods at night in AD patients. The important characteristics of bright light exposure (quantity, spectrum, distribution, timing and duration) for achieving these results in AD patients is not yet understood. Recent research has shown that moderate (~18 lx at the cornea) blue (~470 nm) light is effective at suppressing melatonin in normal humans. It was hypothesized that blue light applied just before AD patients retire to their beds for the night would have a measurable impact on their behavior. A pilot study was conducted for 30 days in a senior health care facility using four individuals diagnosed with mild to moderate levels of dementia. Four AD patients were exposed to arrays of blue light from light emitting diodes (max wavelength = 470 nm) in two-hour sessions (18:00 to 20:00 hours) for 10 days. As a control, they were exposed to red light (max wavelength = 640 nm) in two-hour sessions for 10 days prior to the blue light exposure. Despite the modest sample size, exposure to blue LEDs has shown to affect sleep quality and median body temperature peak of these AD patients. Median body temperature peak was delayed by approximately 2 hours after exposure to blue LEDs compared to exposure to red LEDs and sleep quality was improved. This pilot study demonstrated that light, especially LEDs, can be an important contribution to helping AD patients regulate their circadian functions.
{"title":"Spectral sensitivity of the circadian system","authors":"M. Figueiro, John D. Bullough, M. Rea","doi":"10.1117/12.511856","DOIUrl":"https://doi.org/10.1117/12.511856","url":null,"abstract":"Light exposure regulates several circadian functions in normal humans including the sleep-wake cycle. Individuals with Alzheimer’s Disease (AD) often do not have regular patterns of activity and rest, but, rather, experience random periods of sleep and agitation during both day and night. Bright light during the day and darkness at night has been shown to consolidate activity periods during the day and rest periods at night in AD patients. The important characteristics of bright light exposure (quantity, spectrum, distribution, timing and duration) for achieving these results in AD patients is not yet understood. Recent research has shown that moderate (~18 lx at the cornea) blue (~470 nm) light is effective at suppressing melatonin in normal humans. It was hypothesized that blue light applied just before AD patients retire to their beds for the night would have a measurable impact on their behavior. A pilot study was conducted for 30 days in a senior health care facility using four individuals diagnosed with mild to moderate levels of dementia. Four AD patients were exposed to arrays of blue light from light emitting diodes (max wavelength = 470 nm) in two-hour sessions (18:00 to 20:00 hours) for 10 days. As a control, they were exposed to red light (max wavelength = 640 nm) in two-hour sessions for 10 days prior to the blue light exposure. Despite the modest sample size, exposure to blue LEDs has shown to affect sleep quality and median body temperature peak of these AD patients. Median body temperature peak was delayed by approximately 2 hours after exposure to blue LEDs compared to exposure to red LEDs and sleep quality was improved. This pilot study demonstrated that light, especially LEDs, can be an important contribution to helping AD patients regulate their circadian functions.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114686514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recently, quantum systems with D-dimensional bases states (D > 2) or quDits have attracted much attention in the context of fundamental tests of quantum theory and potential applications in quantum information. In this paper, we discuss several schemes for generating entangled states of two ququarts (four-dimensional quantum systems). The ququart in our scheme is based on frequency-nondegenerate biphoton states of spontaneous parametric down-conversion and we show how the entangled states between two ququarts can be generated with simple linear optical elements, such as an ordinary 50/50 beamsplitter, a polarizing beamsplitter, or a dichroic beamsplitter. We also show that our scheme is capable of generating postselection-free two-ququart entangled states efficiently.
{"title":"Generating entangled states of two ququarts using linear optical elements","authors":"S. Baek, Yoon-Ho Kim","doi":"10.1117/12.698767","DOIUrl":"https://doi.org/10.1117/12.698767","url":null,"abstract":"Recently, quantum systems with D-dimensional bases states (D > 2) or quDits have attracted much attention in the context of fundamental tests of quantum theory and potential applications in quantum information. In this paper, we discuss several schemes for generating entangled states of two ququarts (four-dimensional quantum systems). The ququart in our scheme is based on frequency-nondegenerate biphoton states of spontaneous parametric down-conversion and we show how the entangled states between two ququarts can be generated with simple linear optical elements, such as an ordinary 50/50 beamsplitter, a polarizing beamsplitter, or a dichroic beamsplitter. We also show that our scheme is capable of generating postselection-free two-ququart entangled states efficiently.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114135216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We investigate current density-voltage (J-V) characteristics of copper phthalocyanine thin-film devices, with active areas ranging from S = 1,000,000 to 7.9 μm2, and analyze their charge-carrier transport mechanisms under current densities between nA/cm2 and kA/cm2. We demonstrate injection of 128 kA/cm2 in the smallest device having S = 7.9 μm2. Furthermore, we find that J-V characteristics are divided into three regions between nA/cm2 and kA/cm2: ohm current, shallow-trap space-charge-limited current (SCLC), and trap-free SCLC. In a shallow-trap SCLC region, we observe a large shift in J-V characteristics depending upon the active areas. From analyses of carrier traps with a thermally stimulated current (TSC) measurement, we see that TSC signal intensities of these films decrease as the active area is reduced. Hence, we conclude that a large shift in J-V characteristics is attributable to the change of carrier trap concentrations in these films.
{"title":"Injection of current densities over kA/cm2 in organic thin films and investigation of charge-carrier transport mechanisms in current density region between nA/cm2 and kA/cm2","authors":"T. Matsushima, C. Adachi","doi":"10.1117/12.682122","DOIUrl":"https://doi.org/10.1117/12.682122","url":null,"abstract":"We investigate current density-voltage (J-V) characteristics of copper phthalocyanine thin-film devices, with active areas ranging from S = 1,000,000 to 7.9 μm2, and analyze their charge-carrier transport mechanisms under current densities between nA/cm2 and kA/cm2. We demonstrate injection of 128 kA/cm2 in the smallest device having S = 7.9 μm2. Furthermore, we find that J-V characteristics are divided into three regions between nA/cm2 and kA/cm2: ohm current, shallow-trap space-charge-limited current (SCLC), and trap-free SCLC. In a shallow-trap SCLC region, we observe a large shift in J-V characteristics depending upon the active areas. From analyses of carrier traps with a thermally stimulated current (TSC) measurement, we see that TSC signal intensities of these films decrease as the active area is reduced. Hence, we conclude that a large shift in J-V characteristics is attributable to the change of carrier trap concentrations in these films.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131212093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Solution-processable electrophosphorescent dendrimers are an emerging class of materials for highly efficient light-emitting diodes. Here, we report time-resolved photoluminescence measurements in a fac-tris(2-phenylpyridyl)iridium(III) [Ir(ppy)3]-cored dendrimer in neat film and blended into a 4,4'-bis(N-carbazolyl)biphenyl (CBP) host. Our results identify the existence of a photodegradation process that occurs in solution prior to processing, which significantly affects the photoluminescence kinetics of the films and leads to lower external quantum efficiencies of solution-processed phosphorescent dendrimer light-emitting displays. In parallel, we studied the triplet-triplet exciton annihilation processes in these materials from the photoluminescence decays measured at various excitation densities. From the values of the annihilation rates, we calculated the triplet exciton diffusion lengths and estimated the limiting current densities above which annihilation would dominate in phosphorescent dendrimer light-emitting devices. The results show that the triplet exciton diffusion length is small (<15 nm) in phosphorescent dendrimers and that exciton diffusion becomes still slower in the blends, which can be interpreted by the intermolecular spacing between the phosphorescent emitters being increased, thus reducing the annihilation rate.
{"title":"Phosphorescent iridium(III) cored dendrimers for light-emitting displays","authors":"J. Ribierre, S. Staton, P. Burn, I. Samuel","doi":"10.1117/12.683380","DOIUrl":"https://doi.org/10.1117/12.683380","url":null,"abstract":"Solution-processable electrophosphorescent dendrimers are an emerging class of materials for highly efficient light-emitting diodes. Here, we report time-resolved photoluminescence measurements in a fac-tris(2-phenylpyridyl)iridium(III) [Ir(ppy)3]-cored dendrimer in neat film and blended into a 4,4'-bis(N-carbazolyl)biphenyl (CBP) host. Our results identify the existence of a photodegradation process that occurs in solution prior to processing, which significantly affects the photoluminescence kinetics of the films and leads to lower external quantum efficiencies of solution-processed phosphorescent dendrimer light-emitting displays. In parallel, we studied the triplet-triplet exciton annihilation processes in these materials from the photoluminescence decays measured at various excitation densities. From the values of the annihilation rates, we calculated the triplet exciton diffusion lengths and estimated the limiting current densities above which annihilation would dominate in phosphorescent dendrimer light-emitting devices. The results show that the triplet exciton diffusion length is small (<15 nm) in phosphorescent dendrimers and that exciton diffusion becomes still slower in the blends, which can be interpreted by the intermolecular spacing between the phosphorescent emitters being increased, thus reducing the annihilation rate.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"6333 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130359936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Pflumm, Christian A Gärtner, C. Karnutsch, U. Lemmer
By employing a combined optical/electronic model, we investigate the effect of electronic properties on the performance of three layer organic semiconductor structures, which are a potential candidate for future electrically pumped organic laser diodes. The drift-diffusion equations which describe particle transport are coupled to the spatially inhomogeneous laser rate equations to solve for the dynamics of the excited state and photon population in the laser cavity. Due to the high current densities considered, high particle densities occur, which implies that annihilation processes between the different particle species have to be considered. On the optical side, we take into account the absorption of the metal electrodes required for current injection to obtain the intensity profiles of the guided modes. Our calculations show that the inclusion of annihilation processes leads to a strong dependence of the laser threshold on the charge carrier mobilities, in contrast to the situation when exciton annihilation is neglected. We observe optimum values for the charge carrier mobilities in the emission layer regarding the threshold current and power density. On the other hand, an increase of the mobilities in the transport layers leads to a reduction of these quantities. The threshold voltage decreases for increasing mobilities, regardless of the layer in which the mobility is increased. For optimised values, we obtain a threshold current density of jthr = 267 A/cm2 with annihilation processes taken into account. The presented results can serve as guidelines in the search for material combinations and devices structures suitable for electrically pumped organic semiconductor laser diodes.
通过采用光学/电子组合模型，我们研究了电子特性对三层有机半导体结构性能的影响，这是未来电泵浦有机激光二极管的潜在候选者。将描述粒子输运的漂移扩散方程与空间非均匀激光速率方程耦合，求解了激光腔内激发态和光子居数的动力学。由于考虑了高电流密度，出现了高粒子密度，这意味着必须考虑不同粒子种之间的湮灭过程。在光学方面，我们考虑了注入电流所需的金属电极的吸收，以获得导模的强度分布图。我们的计算表明，湮灭过程的包含导致激光阈值对载流子迁移率的强烈依赖，与忽略激子湮灭的情况相反。我们观察到与阈值电流和功率密度有关的发射层载流子迁移率的最佳值。另一方面，运输层流动性的增加导致这些量的减少。阈值电压随着迁移率的增加而降低，而与迁移率增加的层无关。对于优化值，我们获得了考虑湮灭过程的阈值电流密度jthr = 267 a /cm2。所提出的结果可以为寻找适合电泵有机半导体激光二极管的材料组合和器件结构提供指导。
{"title":"Influence of electronic properties on the threshold behaviour of organic laser diode structures","authors":"C. Pflumm, Christian A Gärtner, C. Karnutsch, U. Lemmer","doi":"10.1117/12.680733","DOIUrl":"https://doi.org/10.1117/12.680733","url":null,"abstract":"By employing a combined optical/electronic model, we investigate the effect of electronic properties on the performance of three layer organic semiconductor structures, which are a potential candidate for future electrically pumped organic laser diodes. The drift-diffusion equations which describe particle transport are coupled to the spatially inhomogeneous laser rate equations to solve for the dynamics of the excited state and photon population in the laser cavity. Due to the high current densities considered, high particle densities occur, which implies that annihilation processes between the different particle species have to be considered. On the optical side, we take into account the absorption of the metal electrodes required for current injection to obtain the intensity profiles of the guided modes. Our calculations show that the inclusion of annihilation processes leads to a strong dependence of the laser threshold on the charge carrier mobilities, in contrast to the situation when exciton annihilation is neglected. We observe optimum values for the charge carrier mobilities in the emission layer regarding the threshold current and power density. On the other hand, an increase of the mobilities in the transport layers leads to a reduction of these quantities. The threshold voltage decreases for increasing mobilities, regardless of the layer in which the mobility is increased. For optimised values, we obtain a threshold current density of jthr = 267 A/cm2 with annihilation processes taken into account. The presented results can serve as guidelines in the search for material combinations and devices structures suitable for electrically pumped organic semiconductor laser diodes.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129167244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Sapochak, A. Padmaperuma, P. Vecchi, Hong Qiao, P. Burrows
High efficiency small molecule organic light emitting devices (OLEDs) based on light emission from an electrophosphorescent dopant dispersed in an organic host matrix are well known. Achieving blue phosphorescent OLEDs is particularly challenging because the host triplet energy should ideally be > 2.8 eV to prevent back-transfer of energy from the dopant to the host matrix resulting in loss of efficiency. A design strategy for developing new host materials with high triplet energies by using phosphine oxide (P=O) moieties as points of saturation in order to build sublimable, electron transporting host materials starting from small, wide bandgap molecular building blocks (i.e., biphenyl, phenyl, naphthalene, octafluorobiphenyl, and N-ethylcarbazole) is described. Electrophosphorescent OLEDs using the organic phosphine oxide compounds as host materials for the sky blue organometallic phosphor, iridium(III)bis(4,6-(di-fluorophenyl)-pyridinato-N,C2,) picolinate (FIrpic) give maximum external quantum efficiencies of ~ 8% and maximum luminance power efficiencies up to 25 lm/W.
{"title":"Design strategies for achieving high triplet energy electron transporting host materials for blue electrophosphorescence","authors":"L. Sapochak, A. Padmaperuma, P. Vecchi, Hong Qiao, P. Burrows","doi":"10.1117/12.684126","DOIUrl":"https://doi.org/10.1117/12.684126","url":null,"abstract":"High efficiency small molecule organic light emitting devices (OLEDs) based on light emission from an electrophosphorescent dopant dispersed in an organic host matrix are well known. Achieving blue phosphorescent OLEDs is particularly challenging because the host triplet energy should ideally be > 2.8 eV to prevent back-transfer of energy from the dopant to the host matrix resulting in loss of efficiency. A design strategy for developing new host materials with high triplet energies by using phosphine oxide (P=O) moieties as points of saturation in order to build sublimable, electron transporting host materials starting from small, wide bandgap molecular building blocks (i.e., biphenyl, phenyl, naphthalene, octafluorobiphenyl, and N-ethylcarbazole) is described. Electrophosphorescent OLEDs using the organic phosphine oxide compounds as host materials for the sky blue organometallic phosphor, iridium(III)bis(4,6-(di-fluorophenyl)-pyridinato-N,C2,) picolinate (FIrpic) give maximum external quantum efficiencies of ~ 8% and maximum luminance power efficiencies up to 25 lm/W.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127817467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Rose, Z. Zhu, C. Madigan, T. Swager, V. Bulović
We demonstrate that attenuated luminescence and lasing in optically excited organic thin films is a sensitive probe to vapours of explosives, such as trinitrotoluene (TNT). The combined chemosensing gains from organic amplifying materials and the lasing action, promise to deliver sensors that can detect explosives with unparalleled sensitivity.
{"title":"Chemosensory lasing action for detection of TNT and other analytes","authors":"A. Rose, Z. Zhu, C. Madigan, T. Swager, V. Bulović","doi":"10.1117/12.683988","DOIUrl":"https://doi.org/10.1117/12.683988","url":null,"abstract":"We demonstrate that attenuated luminescence and lasing in optically excited organic thin films is a sensitive probe to vapours of explosives, such as trinitrotoluene (TNT). The combined chemosensing gains from organic amplifying materials and the lasing action, promise to deliver sensors that can detect explosives with unparalleled sensitivity.","PeriodicalId":406438,"journal":{"name":"SPIE Optics + Photonics","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122498216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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