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Papers by AWNISH TRIPATHI

Research paper thumbnail of Structural, optical and luminescence properties of ZnO thin films: Role of hot electrons defining the luminescence mechanisms

Research paper thumbnail of Comparative Analysis on Depth Control of an Underwater Vehicle

2019 Innovations in Power and Advanced Computing Technologies (i-PACT), 2019

In this paper a kinematic and dynamic model of underwater vehicle has been presented and the dept... more In this paper a kinematic and dynamic model of underwater vehicle has been presented and the depth of the underwater vehicle has been controlled using two different schemes. In one scheme PD controller has been applied to the linearized model and LQR controller has been used in the second scheme. Simulation results are obtained using MATLAB/SIMULINK in both the schemes and the results of the two schemes have been analyzed in the conclusion.

Research paper thumbnail of Grid Impedance Measurement in Low-Voltage Network

Advances in Communication, Devices and Networking, 2019

The performance of the power system can be affected by the variation in grid impedance. Hence, co... more The performance of the power system can be affected by the variation in grid impedance. Hence, continuous monitoring of the grid impedance is very essential. This paper presents a method for the measurement of grid impedance variation in low-voltage network. The estimation method is computationally very simple, and it is dependent on the variance in voltage of the grid at two successive time sampling instants. A quadratic equation is formed using grid voltage. The proposed method is modeled in MATLAB Simulink to measure the grid impedance. Simulation results obtained in MATLAB Simulink are showing or demonstrating the efficacy of the measurement technique for discerning the impedance in low-voltage network.

Research paper thumbnail of Study on the Negative Transconductance in a GaN/AlGaN-Based HEMT

Research paper thumbnail of Numerical study of operational characteristics of dual-gate organic light emitting transistor

The recombination mechanism in Organic light-emitting transistors (OLETs) has been a topic of int... more The recombination mechanism in Organic light-emitting transistors (OLETs) has been a topic of interest as it plays a key role in defining the efficiency of organic tunable LASERs. Efforts have been made to spatially shift the recombination zone towards the middle of the active region for better light outcoupling by proposing various structures. In this regard, the dual gate architecture is found to be a suitable one because of the decreased possibility of exciton quenching. In these devices, two separate opposite polarity carrier channels are formed which diffuse and recombine into the middle of the device and also contribute in drain current. We propose to simulate three possible dual gate configurations to search for a feasible and practical device structure. On analyzing the hole/electron concentration profile and recombination rate at the mid of the device, we find that a partially overlapped configuration is more promising as the emission zone remains in the middle region of th...

Research paper thumbnail of Study on the negative transconductance behaviour in GaAs/AlGaAs based HEMT

The present work intends on reinvestigating the origin of high gate voltage induced negative tran... more The present work intends on reinvestigating the origin of high gate voltage induced negative transconductance characteristics in a GaAs/AlGaAs based High Electron Mobility Transistor (HEMT), as the AlGaAs barrier layer thickness is reduced from 30 nm down to 10 nm. Apart from the decrease in the gate voltage range witnessing positive transconductance, an unprecedented decrement in the slope of positive transconductance is also observed as the barrier layer thickness is scaled down to 10 nm. With such observations in hand, a new fundamental challenge to the scaling of the hetero-layers is raised. This report mainly intends on explaining this transconductance behaviour of the HEMT, using the 3D conduction band energy profile of the barrier layer and the electron density profile of the GaAs channel layer, as provided by TCAD simulations. A high degree of correlation is observed between the transconductance behaviour of the HEMT and the relative difference in the conduction band energie...

Research paper thumbnail of Preparation and Performance Analysis of Graphite Nanoparticle in Domestic Refrigerator

International Journal of Scientific Research in Science, Engineering and Technology, 2021

This article examines experimentally the performance of domestic refrigerators with isobutene (R6... more This article examines experimentally the performance of domestic refrigerators with isobutene (R600a) and graphite nano-lubricants as working fluids. Graphene has an extremely thin layer structure that fills the friction surfaces and reduces friction losses quickly. However, there is a lower coefficient of friction (COF) and higher thermal conductivity of nano-fluids generated using graphite in the base fluid. The graphite nanoparticles modified in the surface are verified to continuously suspend for a long period of time in the form of clusters. The refrigeration test examined the application of the graphite nano-lubricants in the domestic refrigerator with a volume concentration of 0.1%, 0.3%, and 0.5%. The findings show that nano-refrigerants in the refrigeration system work safely and normally. And also compressor and refrigerator output have been analyzed. Moreover, refrigerator energy usage decreased by 15.26%, 17.10%, and 21.16% with graphite nano-lubricant as a concentration...

Research paper thumbnail of Preparation and Performance Analysis of Graphite Nanoparticle in Domestic Refrigerator

This article examines experimentally the performance of domestic refrigerators with isobutene (R6... more This article examines experimentally the performance of domestic refrigerators with isobutene (R600a) and graphite nano-lubricants as working fluids. Graphene has an extremely thin layer structure that fills the friction surfaces and reduces friction losses quickly. However, there is a lower coefficient of friction (COF) and higher thermal conductivity of nano-fluids generated using graphite in the base fluid. The graphite nanoparticles modified in the surface are verified to continuously suspend for a long period of time in the form of clusters. The refrigeration test examined the application of the graphite nano-lubricants in the domestic refrigerator with a volume concentration of 0.1%, 0.3%, and 0.5%. The findings show that nano-refrigerants in the refrigeration system work safely and normally. And also compressor and refrigerator output have been analyzed. Moreover, refrigerator energy usage decreased by 15.26%, 17.10%, and 21.16% with graphite nano-lubricant as a concentration...

Research paper thumbnail of Effect of Ge doping on the electrical properties of amorphous Zn–Sn–O thin films

Research paper thumbnail of Synthesis, Photophysical, and Electroluminescent Properties of Arylenevinylenes- co -pyrrolenevinylenes Derived from Divinylaryl Bridged Bispyrroles

Macromolecules, Apr 1, 2007

Synthesis, characterization, and photophysical properties of four different π-conjugated oligomer... more Synthesis, characterization, and photophysical properties of four different π-conjugated oligomers containing alternate arylenevinylene and pyrrolenevinylene repeat units are reported. The optoelectronic properties are traced from the molecules to oligomers and to thin films and single layer ...

Research paper thumbnail of Review on Conventional and Green Synthesis Methodologies of Iron Oxide Based Magnetic Nanoparticles

Advanced Science Letters, 2015

Research paper thumbnail of Time Analyzed Transient Spectroscopy to Monitor Carrier Dynamics at Deep Level Defects in Polymeric Semiconductors

Research paper thumbnail of Electroluminescence transient of polymer light emitting diodes: field dependence of overshoot and time delay

2007 International Workshop on Physics of Semiconductor Devices, 2007

... (b) MEH-PPV Awnish K. Tripathi, Rajneesh Verma, Anand K.Biswas, Ashish, and YNMohapatra ... f... more ... (b) MEH-PPV Awnish K. Tripathi, Rajneesh Verma, Anand K.Biswas, Ashish, and YNMohapatra ... followed by spincoating of a thin layer of polyethylene dioxythiophene / polystyrenesulfonate (PEDOT: PSS) and baked at 120 °C for 2 h under vacuum. ...

Research paper thumbnail of Effect of condensed phase environment on luminescent properties of MEH-PPV thin films

Synthetic Metals, 2005

We study sensitivity of photoluminescence emission properties to state of aggregation in MEH-PPV ... more We study sensitivity of photoluminescence emission properties to state of aggregation in MEH-PPV thin films, and its solution in chloroform and xylene (50:50) mixture from which these films are either spin-cast or drop-cast. The choice of composition of solvent is dictated by the ease of fabrication of devices. We demonstrate unambiguous correlation between relative peak heights of the two characteristic major peaks in steady state photoluminescence with processing parameters, such as spin speed, and show that their ratio can be used as a robust measure of degree of entangled packing both in films and solutions. In thin films, a small but discernible red shift of about 3-10 nm in PL peak positions, and increase in width of peaks is observed with changes in degree of packing. A comparison of PL decay dynamics at the 588 nm emission shows that the decay develops slower components with increase in entangled packing in the case of thin films as compared to the fast nearly exponential decay in the case of solution. The progressive slowing down of dynamics is attributed to shift in distribution of inter-chain species of excitons in thin films.

Research paper thumbnail of Simultaneous and direct measurement of carrier diffusion constant and mobility in organic semiconductors and deviation from standard Einstein relation

Physical Review B, 2011

Page 1. RAPID COMMUNICATIONS PHYSICAL REVIEW B 84, 041201(R) (2011) Simultaneous and direct measu... more Page 1. RAPID COMMUNICATIONS PHYSICAL REVIEW B 84, 041201(R) (2011) Simultaneous and direct measurement of carrier diffusion constant and mobility in organic semiconductors and deviation from standard Einstein relation ...

Research paper thumbnail of Correlation of photocurrent and electroabsorption spectra and their temperature dependence for conjugated light emitting polymers: The origin of the corresponding density of states

Physical Review B, 2011

ABSTRACT

Research paper thumbnail of Mobility with negative coefficient in Poole–Frenkel field dependence in conjugated polymers: Role of injected hot electrons

Organic Electronics, 2010

In this work we study the electric field dependence of mobility extracted from Electroluminescenc... more In this work we study the electric field dependence of mobility extracted from Electroluminescence Transient (ELT) measurements in both single carrier and double carrier Polymer Light emitting Diode (PLED) configurations by varying the cathode. We have chosen two different families of conjugated light emitting polymers (structurally different hole transporting materials). The Poole-Frenkel (P-F) plot of mobility l as a function electric field F (log l / ffiffiffi F p) shows negative slope (b < 0) in the case of double carrier injection, while positive slope is observed as expected in the case of dominantly single carrier injection. The mobility values and their corresponding field dependent parameters for both the carriers are derived. It is shown that electrons injected to higher lying transport states can have high mobilities behaving as hot electrons. We propose a phenomenological model based on alignment of Gaussian local density of states (DOS) to explain the occurrence of reduction of mobility with increasing electric field for electrons, which do not fully relax into equilibrium distribution within the DOS in the timescales of transit time.

Research paper thumbnail of Mobility determination using frequency dependence of imaginary part of impedance (Im Z) for organic and polymeric thin films

Applied Physics Letters, 2011

Mobility determination using frequency dependence of imaginary part of impedance (Im Z) for organ... more Mobility determination using frequency dependence of imaginary part of impedance (Im Z) for organic and polymeric thin films. [Applied Physics Letters 98, 033304 (2011)]. Durgesh C. Tripathi, Awnish K. Tripathi, YN Mohapatra. Abstract. ...

Research paper thumbnail of Photoluminescence quantum efficiency (PLQE) and PL decay characteristics of polymeric light emitting materials

Synthetic metals, 2005

We report photoluminescence quantum efficiency (PLQE) measurements on thin films of a variety of ... more We report photoluminescence quantum efficiency (PLQE) measurements on thin films of a variety of in-house synthesized conjugated polymers such as PPV, MEH-PPV and CN-PPV with improved techniques using integrating sphere and synchronous detection. Our method allows use ...

Research paper thumbnail of Structural, optical and luminescence properties of ZnO thin films: Role of hot electrons defining the luminescence mechanisms

Research paper thumbnail of Comparative Analysis on Depth Control of an Underwater Vehicle

2019 Innovations in Power and Advanced Computing Technologies (i-PACT), 2019

In this paper a kinematic and dynamic model of underwater vehicle has been presented and the dept... more In this paper a kinematic and dynamic model of underwater vehicle has been presented and the depth of the underwater vehicle has been controlled using two different schemes. In one scheme PD controller has been applied to the linearized model and LQR controller has been used in the second scheme. Simulation results are obtained using MATLAB/SIMULINK in both the schemes and the results of the two schemes have been analyzed in the conclusion.

Research paper thumbnail of Grid Impedance Measurement in Low-Voltage Network

Advances in Communication, Devices and Networking, 2019

The performance of the power system can be affected by the variation in grid impedance. Hence, co... more The performance of the power system can be affected by the variation in grid impedance. Hence, continuous monitoring of the grid impedance is very essential. This paper presents a method for the measurement of grid impedance variation in low-voltage network. The estimation method is computationally very simple, and it is dependent on the variance in voltage of the grid at two successive time sampling instants. A quadratic equation is formed using grid voltage. The proposed method is modeled in MATLAB Simulink to measure the grid impedance. Simulation results obtained in MATLAB Simulink are showing or demonstrating the efficacy of the measurement technique for discerning the impedance in low-voltage network.

Research paper thumbnail of Study on the Negative Transconductance in a GaN/AlGaN-Based HEMT

Research paper thumbnail of Numerical study of operational characteristics of dual-gate organic light emitting transistor

The recombination mechanism in Organic light-emitting transistors (OLETs) has been a topic of int... more The recombination mechanism in Organic light-emitting transistors (OLETs) has been a topic of interest as it plays a key role in defining the efficiency of organic tunable LASERs. Efforts have been made to spatially shift the recombination zone towards the middle of the active region for better light outcoupling by proposing various structures. In this regard, the dual gate architecture is found to be a suitable one because of the decreased possibility of exciton quenching. In these devices, two separate opposite polarity carrier channels are formed which diffuse and recombine into the middle of the device and also contribute in drain current. We propose to simulate three possible dual gate configurations to search for a feasible and practical device structure. On analyzing the hole/electron concentration profile and recombination rate at the mid of the device, we find that a partially overlapped configuration is more promising as the emission zone remains in the middle region of th...

Research paper thumbnail of Study on the negative transconductance behaviour in GaAs/AlGaAs based HEMT

The present work intends on reinvestigating the origin of high gate voltage induced negative tran... more The present work intends on reinvestigating the origin of high gate voltage induced negative transconductance characteristics in a GaAs/AlGaAs based High Electron Mobility Transistor (HEMT), as the AlGaAs barrier layer thickness is reduced from 30 nm down to 10 nm. Apart from the decrease in the gate voltage range witnessing positive transconductance, an unprecedented decrement in the slope of positive transconductance is also observed as the barrier layer thickness is scaled down to 10 nm. With such observations in hand, a new fundamental challenge to the scaling of the hetero-layers is raised. This report mainly intends on explaining this transconductance behaviour of the HEMT, using the 3D conduction band energy profile of the barrier layer and the electron density profile of the GaAs channel layer, as provided by TCAD simulations. A high degree of correlation is observed between the transconductance behaviour of the HEMT and the relative difference in the conduction band energie...

Research paper thumbnail of Preparation and Performance Analysis of Graphite Nanoparticle in Domestic Refrigerator

International Journal of Scientific Research in Science, Engineering and Technology, 2021

This article examines experimentally the performance of domestic refrigerators with isobutene (R6... more This article examines experimentally the performance of domestic refrigerators with isobutene (R600a) and graphite nano-lubricants as working fluids. Graphene has an extremely thin layer structure that fills the friction surfaces and reduces friction losses quickly. However, there is a lower coefficient of friction (COF) and higher thermal conductivity of nano-fluids generated using graphite in the base fluid. The graphite nanoparticles modified in the surface are verified to continuously suspend for a long period of time in the form of clusters. The refrigeration test examined the application of the graphite nano-lubricants in the domestic refrigerator with a volume concentration of 0.1%, 0.3%, and 0.5%. The findings show that nano-refrigerants in the refrigeration system work safely and normally. And also compressor and refrigerator output have been analyzed. Moreover, refrigerator energy usage decreased by 15.26%, 17.10%, and 21.16% with graphite nano-lubricant as a concentration...

Research paper thumbnail of Preparation and Performance Analysis of Graphite Nanoparticle in Domestic Refrigerator

This article examines experimentally the performance of domestic refrigerators with isobutene (R6... more This article examines experimentally the performance of domestic refrigerators with isobutene (R600a) and graphite nano-lubricants as working fluids. Graphene has an extremely thin layer structure that fills the friction surfaces and reduces friction losses quickly. However, there is a lower coefficient of friction (COF) and higher thermal conductivity of nano-fluids generated using graphite in the base fluid. The graphite nanoparticles modified in the surface are verified to continuously suspend for a long period of time in the form of clusters. The refrigeration test examined the application of the graphite nano-lubricants in the domestic refrigerator with a volume concentration of 0.1%, 0.3%, and 0.5%. The findings show that nano-refrigerants in the refrigeration system work safely and normally. And also compressor and refrigerator output have been analyzed. Moreover, refrigerator energy usage decreased by 15.26%, 17.10%, and 21.16% with graphite nano-lubricant as a concentration...

Research paper thumbnail of Effect of Ge doping on the electrical properties of amorphous Zn–Sn–O thin films

Research paper thumbnail of Synthesis, Photophysical, and Electroluminescent Properties of Arylenevinylenes- co -pyrrolenevinylenes Derived from Divinylaryl Bridged Bispyrroles

Macromolecules, Apr 1, 2007

Synthesis, characterization, and photophysical properties of four different π-conjugated oligomer... more Synthesis, characterization, and photophysical properties of four different π-conjugated oligomers containing alternate arylenevinylene and pyrrolenevinylene repeat units are reported. The optoelectronic properties are traced from the molecules to oligomers and to thin films and single layer ...

Research paper thumbnail of Review on Conventional and Green Synthesis Methodologies of Iron Oxide Based Magnetic Nanoparticles

Advanced Science Letters, 2015

Research paper thumbnail of Time Analyzed Transient Spectroscopy to Monitor Carrier Dynamics at Deep Level Defects in Polymeric Semiconductors

Research paper thumbnail of Electroluminescence transient of polymer light emitting diodes: field dependence of overshoot and time delay

2007 International Workshop on Physics of Semiconductor Devices, 2007

... (b) MEH-PPV Awnish K. Tripathi, Rajneesh Verma, Anand K.Biswas, Ashish, and YNMohapatra ... f... more ... (b) MEH-PPV Awnish K. Tripathi, Rajneesh Verma, Anand K.Biswas, Ashish, and YNMohapatra ... followed by spincoating of a thin layer of polyethylene dioxythiophene / polystyrenesulfonate (PEDOT: PSS) and baked at 120 °C for 2 h under vacuum. ...

Research paper thumbnail of Effect of condensed phase environment on luminescent properties of MEH-PPV thin films

Synthetic Metals, 2005

We study sensitivity of photoluminescence emission properties to state of aggregation in MEH-PPV ... more We study sensitivity of photoluminescence emission properties to state of aggregation in MEH-PPV thin films, and its solution in chloroform and xylene (50:50) mixture from which these films are either spin-cast or drop-cast. The choice of composition of solvent is dictated by the ease of fabrication of devices. We demonstrate unambiguous correlation between relative peak heights of the two characteristic major peaks in steady state photoluminescence with processing parameters, such as spin speed, and show that their ratio can be used as a robust measure of degree of entangled packing both in films and solutions. In thin films, a small but discernible red shift of about 3-10 nm in PL peak positions, and increase in width of peaks is observed with changes in degree of packing. A comparison of PL decay dynamics at the 588 nm emission shows that the decay develops slower components with increase in entangled packing in the case of thin films as compared to the fast nearly exponential decay in the case of solution. The progressive slowing down of dynamics is attributed to shift in distribution of inter-chain species of excitons in thin films.

Research paper thumbnail of Simultaneous and direct measurement of carrier diffusion constant and mobility in organic semiconductors and deviation from standard Einstein relation

Physical Review B, 2011

Page 1. RAPID COMMUNICATIONS PHYSICAL REVIEW B 84, 041201(R) (2011) Simultaneous and direct measu... more Page 1. RAPID COMMUNICATIONS PHYSICAL REVIEW B 84, 041201(R) (2011) Simultaneous and direct measurement of carrier diffusion constant and mobility in organic semiconductors and deviation from standard Einstein relation ...

Research paper thumbnail of Correlation of photocurrent and electroabsorption spectra and their temperature dependence for conjugated light emitting polymers: The origin of the corresponding density of states

Physical Review B, 2011

ABSTRACT

Research paper thumbnail of Mobility with negative coefficient in Poole–Frenkel field dependence in conjugated polymers: Role of injected hot electrons

Organic Electronics, 2010

In this work we study the electric field dependence of mobility extracted from Electroluminescenc... more In this work we study the electric field dependence of mobility extracted from Electroluminescence Transient (ELT) measurements in both single carrier and double carrier Polymer Light emitting Diode (PLED) configurations by varying the cathode. We have chosen two different families of conjugated light emitting polymers (structurally different hole transporting materials). The Poole-Frenkel (P-F) plot of mobility l as a function electric field F (log l / ffiffiffi F p) shows negative slope (b < 0) in the case of double carrier injection, while positive slope is observed as expected in the case of dominantly single carrier injection. The mobility values and their corresponding field dependent parameters for both the carriers are derived. It is shown that electrons injected to higher lying transport states can have high mobilities behaving as hot electrons. We propose a phenomenological model based on alignment of Gaussian local density of states (DOS) to explain the occurrence of reduction of mobility with increasing electric field for electrons, which do not fully relax into equilibrium distribution within the DOS in the timescales of transit time.

Research paper thumbnail of Mobility determination using frequency dependence of imaginary part of impedance (Im Z) for organic and polymeric thin films

Applied Physics Letters, 2011

Mobility determination using frequency dependence of imaginary part of impedance (Im Z) for organ... more Mobility determination using frequency dependence of imaginary part of impedance (Im Z) for organic and polymeric thin films. [Applied Physics Letters 98, 033304 (2011)]. Durgesh C. Tripathi, Awnish K. Tripathi, YN Mohapatra. Abstract. ...

Research paper thumbnail of Photoluminescence quantum efficiency (PLQE) and PL decay characteristics of polymeric light emitting materials

Synthetic metals, 2005

We report photoluminescence quantum efficiency (PLQE) measurements on thin films of a variety of ... more We report photoluminescence quantum efficiency (PLQE) measurements on thin films of a variety of in-house synthesized conjugated polymers such as PPV, MEH-PPV and CN-PPV with improved techniques using integrating sphere and synchronous detection. Our method allows use ...