Organic Semiconductor Devices for Light Detection (Springer Theses)

✍ Scribed by Jonas Kublitski

• Publisher: Springer
• Year: 2022
• Tongue: English
• Leaves: 211
• Category: Library

✦ Synopsis

In recent decades, the way human beings interact with technology has been significantly transformed. In our daily life, ever fewer manually controlled devices are used, giving way to automatized houses, cars, and devices. A significant part of this technological revolution relies on signal detection and evaluation, placing detectors as core devices for further technological developments. This book introduces a versatile contribution to achieving light sensing: Organic Semiconductor Devices for Light Detection. The text is organized to guide the reader through the main concepts of light detection, followed by a introduction to the semiconducting properties of organic molecular solids. The sources of non-idealities in organic photodetectors are presented in chapter 5, and a new device concept, which aims to overcome some of the limitation discussed in the previous chapters, is demonstrated. Finally, an overview of the field is given with a selection of open points for future investigation.

✦ Table of Contents

Supervisor’s Foreword
Abstract
Acknowledgments
Contents
Symbols, Physical Constants and Acronyms
Symbols
Physical Constants
Acronyms
1 Introduction
1.1 Detection of Electromagnetic Radiation: A Growing Demand
1.2 Challenges of the Current Technology
1.3 Organic Electronics and Organic Photodetectors
1.4 Challenges for OPDs
1.5 Outline of This Thesis
References
2 Fundamentals of Light Detection
2.1 Radiometry
2.1.1 Radiometric Quantities
2.1.2 Black-Body Radiation
2.2 Inorganic Light Detecting Devices
2.2.1 Fundamentals of Inorganic Semiconductor Physics
2.2.2 From Radiation to Chemical Energy
2.2.3 From Chemical Energy to Electrical Energy
2.2.4 Interfaces Metal/Semiconductor
2.2.5 pn-Junction
2.2.6 Photoconductors for Light Detection
2.3 Figures of Merit of Photodetectors
2.3.1 Power Spectral Density Sx(f)
2.3.2 Noise Current langleinrangle
2.3.3 Responsivity mathcalR
2.3.4 Noise Equivalent Power NEP
2.3.5 Specific Detectivity D
2.3.6 BLIP Limit for D
2.3.7 Dynamic Range
2.3.8 Response Speed
References
3 Organic Semiconductors for Light Detection
3.1 Organic Semiconductors
3.1.1 Molecular Properties
3.1.2 Solid State Physics of Organic Semiconductors
3.1.3 Traps in Organic Solids
3.2 Working Principle of Optoelectronic Devices
3.2.1 Donor-Acceptor Systems and Charge-Transfer States
3.2.2 Impact of Charge-Transfer States on Optoelectronic Devices
3.2.3 From Light Absorption to Electric Output
3.2.4 Organic Photodetectors
3.2.5 Photomultiplication-Type OPDs
References
4 Materials and Experimental Methods
4.1 Sample Preparation
4.2 Materials
4.2.1 Donors
4.2.2 Acceptors
4.2.3 Hole Transporting Layers
4.2.4 Electron Transporting Layers
4.2.5 Dopants
4.3 Characterization Methods
4.3.1 Temperature-Dependent Electric Measurements
4.3.2 Current-Voltage Measurements
4.3.3 Temperature-Dependent Current-Voltage Measurements
4.3.4 Suns-VOC Measurements
4.3.5 External Quantum Efficiency Measurements
4.3.6 Sensitive External Quantum Efficiency Measurements
4.3.7 Noise Measurements
4.3.8 Impedance Spectroscopy
4.3.9 Transient Photocurrent Measurements
4.3.10 Spectroscopic Ellipsometry Measurements
4.4 Drift-Diffusion JV-Simulation
References
5 Reverse Dark Current in Organic Photodetectors: Generation Paths in Fullerene Based Devices
5.1 Introduction
5.2 The Role of Dark Current on the Specific Detectivity
5.3 Device Optimization for Dark Current Studies
5.3.1 Contact Selectivity and Blocking Layers
5.3.2 Shunt Paths in OPDs
5.3.3 Device Structuring
5.4 Diode Saturation Current Generated via Charge-Transfer States
5.5 Traps as the Main Source of Reverse Dark Current in OPDs
5.6 Generation-Recombination Statistics Due to a Distribution …
5.6.1 Trap-Assisted JD Generation Model
5.6.2 Modeling Trap-Assisted JD Generation in OPDs
5.6.3 Ideality Factor in Trap-Assisted JD
5.6.4 Arrhenius Activation Energy of Trap States
5.6.5 The Impact of the Trap Distribution Characteristics on JD
5.6.6 The Interplay Between CT States and Trap States
5.7 Conclusion
References
6 Enhancing Sub-Bandgap External Quantum Efficiency by Photomultiplication in Narrowband Organic Near-Infrared Photodetectors
6.1 Introduction
6.2 Photomultiplication in ZnPc:C60 Devices
6.2.1 Enhancing the External Quantum Efficiency
6.2.2 Effect of Acceptor Concentration on Photomultiplication
6.2.3 The Role of Dark Current in PM-OPDs
6.2.4 Enhancement of Charge-Transfer State Response in PM-OPDs
6.2.5 Transient Photocurrent
6.3 Dynamic Range of PM-OPDs
6.4 Conclusion
References
7 Summary and Outlook
7.1 Summary
7.1.1 On the Origin of the Dark Current of Organic Photodetectors
7.1.2 Enhancing EQE via Photomultiplication in Organic Photodetectors
7.1.3 Related Topics Investigated Alongside with this Thesis (Not Shown)
7.2 Outlook
7.2.1 Open Research Topics for Photovoltaic-Type OPDs
7.2.2 Open Research Topics for Photomultiplication-Type OPDs
7.2.3 Open Research Topics for OPDs in General
References
Appendix Impedance Spectroscopy in Organic Blends
Appendix Curriculum Vitae
Professional Experience
Academic Projects
Academic Education with Degree
Non-academic Education
Publications
Attended Conferences
Prizes and Awards
Funding Received So Far
Supervising and Mentoring Activities
Languages
Knowledge Area
Referees