7 results on '"Boning Qu"'
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2. Robust constrained tension control for high-precision roll-to-roll processes
- Author
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Zhiyi Chen, Boning Qu, Baoyang Jiang, Stephen R. Forrest, and Jun Ni
- Subjects
Control and Systems Engineering ,Applied Mathematics ,Electrical and Electronic Engineering ,Instrumentation ,Computer Science Applications - Abstract
Tension control is critical for maintaining good product quality in most roll-to-roll (R2R) production systems. Previous work has primarily focused on improving the disturbance rejection performance of tension controllers. Here, a robust linear parameter-varying model predictive control (LPV-MPC) scheme is designed to enhance the tension tracking performance of a pilot R2R system for deposition of materials used in flexible thin film applications. The performance of a tension controller may degrade due to disturbances associated with model uncertainties and the slowly-changing dynamics in R2R systems. We introduce a method that separately treats these two sources of disturbance. The controller utilizes an incremental model to eliminate the errors caused by the mismatch between the nominal model and the actual system. A tube-based MPC formulation combined with scheduled parameters adequately updates models and corrects for the time-varying dynamics. Constraints on the rated motor torque are incorporated in the MPC to maintain the controller reliability and avoid machine failures. We illustrate the operation of our control algorithm through simulation of an actual R2R system. The controller outperforms the benchmarks in terms of fast transient response and offset-free tension tracking. It also demonstrates immunity from variations due to parametric uncertainties.
- Published
- 2022
3. Color-neutral, semitransparent organic photovoltaics for power window applications
- Author
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Stephen R. Forrest, Zhengxing Peng, Yongxi Li, Hongping Yan, Xia Guo, Boning Qu, Harald Ade, and Maojie Zhang
- Subjects
Multidisciplinary ,Materials science ,Organic solar cell ,business.industry ,Band gap ,Photovoltaic system ,Color temperature ,Acceptor ,Indium tin oxide ,Anode ,Physical Sciences ,Optoelectronics ,Chromaticity ,business - Abstract
Semitransparent organic photovoltaic cells (ST-OPVs) are emerging as a solution for solar energy harvesting on building facades, rooftops, and windows. However, the trade-off between power-conversion efficiency (PCE) and the average photopic transmission (APT) in color-neutral devices limits their utility as attractive, power-generating windows. A color-neutral ST-OPV is demonstrated by using a transparent indium tin oxide (ITO) anode along with a narrow energy gap nonfullerene acceptor near-infrared (NIR) absorbing cell and outcoupling (OC) coatings on the exit surface. The device exhibits PCE = 8.1 ± 0.3% and APT = 43.3 ± 1.2% that combine to achieve a light-utilization efficiency of LUE = 3.5 ± 0.1%. Commission Internationale d’eclairage chromaticity coordinates of (0.38, 0.39), a color-rendering index of 86, and a correlated color temperature of 4,143 K are obtained for simulated AM1.5 illumination transmitted through the cell. Using an ultrathin metal anode in place of ITO, we demonstrate a slightly green-tinted ST-OPV with PCE = 10.8 ± 0.5% and APT = 45.7 ± 2.1% yielding LUE = 5.0 ± 0.3% These results indicate that ST-OPVs can combine both efficiency and color neutrality in a single device.
- Published
- 2020
4. Fast Organic Vapor Phase Deposition of Thin Films in Light-Emitting Diodes
- Author
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Steven Morris, Kai Sun, Boning Qu, Max Shtein, Shaocong Hou, Kan Ding, and Stephen R. Forrest
- Subjects
Materials science ,business.industry ,Doping ,General Engineering ,Nucleation ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,law ,OLED ,Optoelectronics ,Deposition (phase transition) ,Phosphorescent organic light-emitting diode ,General Materials Science ,Quantum efficiency ,Thin film ,0210 nano-technology ,business ,Layer (electronics) - Abstract
Fast deposition of thin films is essential for achieving low-cost, high-throughput phosphorescent organic light-emitting diode (PHOLED) production. In this work, we demonstrate rapid and uniform growth of semiconductor thin films by organic vapor phase deposition (OVPD). A green PHOLED comprising an emission layer (EML) grown at 50 A/s with bis[2-(2-pyridinyl-N)phenyl-C](acetylacetonato)iridium(III) (Ir(ppy)2(acac)) doped into 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP) exhibits a maximum external quantum efficiency of 20 ± 1%. The morphology, charge transport properties, and radiative efficiency under optical and electrical excitation of the PHOLED EML are investigated as functions of the deposition rate via both experimental and theoretical approaches. The EML shows no evidence for gas phase nucleation of the organic molecules at deposition rates as high as 50 A/s. However, the roll-off in quantum efficiency at high current progressively increases with deposition rate due to enhanced triplet-polaron annihilation. The roll-off results from accumulation of stress within the PHOLED EML that generates a high density of defect states. The defects, in turn, act as recombination sites for triplets and hole polarons, leading to enhanced triplet-polaron annihilation at high current. We introduce a void nucleation model to describe the film morphology evolution that is observed using electron microscopy.
- Published
- 2020
5. Aperiodic optical coatings for neutral-color semi-transparent organic photovoltaics
- Author
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Stephen R. Forrest, Boning Qu, Hafiz K. M. Sheriff, and Yongxi Li
- Subjects
010302 applied physics ,Materials science ,Physics and Astronomy (miscellaneous) ,Organic solar cell ,business.industry ,Energy conversion efficiency ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Transfer matrix ,Color rendering index ,Optical coating ,Aperiodic graph ,0103 physical sciences ,Transmittance ,Optoelectronics ,Chromaticity ,0210 nano-technology ,business - Abstract
Semi-transparent organic photovoltaics (ST-OPVs) have the potential for integration with windows for ubiquitous power generating applications. Typically, such applications require that ST-OPVs be neutrally transparent across the visible and exhibit both a high average photopic transmittance (APT) and color rendering index, as well as iso-energetic chromaticity coordinates. In this work, we demonstrate the design and use of optical coatings to achieve ST-OPVs with a neutral visible transmittance of APT = 50%, a power conversion efficiency of 8.3%, and optical properties that are independent of a ± 30° variation in the solar angle of incidence. These simple optical coatings are rapidly designed using a genetic algorithm and transfer matrix formalism.
- Published
- 2021
6. Color-neutral, semitransparent organic photovoltaics for power window applications.
- Author
-
Yongxi Li, Xia Guo, Zhengxing Peng, Boning Qu, Hongping Yan, Ade, Harald, Zhang, Maojie, and Forrest, Stephen R.
- Subjects
PHOTOVOLTAIC power generation ,ENERGY harvesting ,PHOTOVOLTAIC cells ,INDIUM tin oxide ,SOLAR energy - Abstract
Semitransparent organic photovoltaic cells (ST-OPVs) are emerging as a solution for solar energy harvesting on building facades, rooftops, and windows. However, the trade-off between powerconversion efficiency (PCE) and the average photopic transmission (APT) in color-neutral devices limits their utility as attractive, power-generating windows. A color-neutral ST-OPV is demonstrated by using a transparent indium tin oxide (ITO) anode along with a narrow energy gap nonfullerene acceptor near-infrared (NIR) absorbing cell and outcoupling (OC) coatings on the exit surface. The device exhibits PCE = 8.1 ± 0.3% and APT = 43.3 ± 1.2% that combine to achieve a light-utilization efficiency of LUE = 3.5 ± 0.1%. Commission Internationale d’eclairage chromaticity coordinates of (0.38, 0.39), a color-rendering index of 86, and a correlated color temperature of 4,143 K are obtained for simulated AM1.5 illumination transmitted through the cell. Using an ultrathin metal anode in place of ITO, we demonstrate a slightly green-tinted STOPV with PCE = 10.8 ± 0.5% and APT = 45.7 ± 2.1% yielding LUE = 5.0 ± 0.3% These results indicate that ST-OPVs can combine both efficiency and color neutrality in a single device. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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7. Continuous roll-to-roll fabrication of organic photovoltaic cells via interconnected high-vacuum and low-pressure organic vapor phase deposition systems
- Author
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Stephen R. Forrest and Boning Qu
- Subjects
Fabrication ,Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Ultra-high vacuum ,02 engineering and technology ,Substrate (electronics) ,Chemical vapor deposition ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Roll-to-roll processing ,Surface roughness ,Deposition (phase transition) ,Optoelectronics ,Thin film ,0210 nano-technology ,business - Abstract
We demonstrate continuous roll-to-roll (R2R) fabrication of single junction and tandem organic photovoltaic (OPV) cells on flexible plastic substrates employing a system that integrates organic deposition by high vacuum thermal evaporation (VTE) and low pressure organic vapor phase deposition (OVPD). By moving the substrate from chamber to chamber and then depositing films on stationary substrates, we achieve power conversion efficiencies of PCE = 8.6 ± 0.3% and 8.9 ± 0.2% for the single junction and tandem cells, respectively. Single junction OPVs are also fabricated on a continuously translating substrate at 0.3 cm/s, to achieve PCE = 8.5 ± 0.2%. Thin films grown on translating substrates by OVPD show
- Published
- 2018
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