Drain Current vs. Drain - Source Voltage for P3HT OTFT [7] Drain Current vs. Gate - Source Voltage for P3HT OTFT [7] MDMO-PPV PCBM Absorbance Spectra [5] ITO 4.8 eV PEDOT:PSS 5.0 eV Ga-In 4.2 eV + + + - - - 1 2 3 4 T 4 LUMO 3.7 eV HOMO 6.1 eV LUMO 3.0 eV HOMO 5.3 eV PCBM MDMO-PPV Optoelectronics & Lightwave Engineering Group Electrical & Computer Engineering Laboratory Teaching Modules on Laboratory Teaching Modules on Organic Electronics & Liquid Crystal Displays Organic Electronics & Liquid Crystal Displays for Undergraduate & Graduate Education for Undergraduate & Graduate Education Dr. Michael J. Escuti Assistant Professor mjesctui@ncsu.edu mjesctui@ncsu.edu Brandon L. Conover PhD Student blconove@ncsu.edu blconove@ncsu.edu Objectives Dissemination Overall Goal: To develop a series of laboratory modules that afford hands-on experience with Organic Electronic Materials Organic Electronic Materials & Liquid Crystal Display Technology Liquid Crystal Display Technology Guiding Principles: Guiding Principles: - Hands-on instruction - Low-cost infrastructure - Multidisciplinary background Target Students Target Students: Graduate & Advanced Undergraduate in: Physics - Electrical Engineering - Materials Science Educational Topics: Educational Topics: - Self-Assembly - Partial Order - Polymer Science - Fabrication Methods - Light Emission / Absorption / Polarization - Charge Injection / Transport in Organic Materials - Electrical / Optical Characterization Concepts & Devices http://www.ece.ncsu.edu/oleg/wiki/NSF_Lab_Modules http://www.ece.ncsu.edu/oleg/wiki/NSF_Lab_Modules Freely available online: all lab documents (background, procedure, prelab) bill of materials / parts / vendors / assembly tips examples of student work companion course materials Workshop in Spring ‘09 inviting local and international educators: perform lab moduels present related research Liquid Crystal Display (LCD) Pixel Educational Topics [1]: Educational Topics [1]: - Polarization of Light - Polarizers - Partial Order - Optical Transmittance - Liquid Crystal Chemistry - Photonic Characterization Electrode [ITO] Rubbed Alignment Layer [PVA] Rubbed Alignment Layer [PVA] Nematic Liquid Crystal Layer Substrate [Glass] Electrode [ITO] Substrate [Glass] Polarizer Polarizer Alignment Material TN Mode OFF ON Measurement Set-Up C 5 H 11 CN Polymer Light-Emitting Diode (OLED) Anode [ITO] Hole Transport Layer [PEDOT:PSS] Substrate [Glass] Cathode [GaIn] Sealant / Adhesive Substrate [Glass] Conductive Film [ITO] Light-Emitting Layer [MEH-PPV] PEDOT:PSS MEH-PPV Ga-In 4.2 eV Ca 2.8 eV Ag 4.1 eV ITO 4.8 eV LUMO 2.7 eV LUMO 2.2 eV HOMO 5.2 eV HOMO 5.0 eV + + - - 4 ##.# V Voltmeter + + + - - - ##.# A Ammeter Anode Cathode Photodiode Optical Power Meter ##.# W DC Power Supply Measurement Set-Up MEH - PPV Characteristics Absorbance - Abs Electroluminescence - EL Photoluminescence - PL Polymer Photovoltaic Solar Cell (OPV) Educational Topics [4,5]: Educational Topics [4,5]: - Power Generation - Charge Transport - Polymer Science - Excition Creation - Measurement of Solar Cell Eiciencies Anode [ITO] Conducting Layer [PEDOT:PSS] Photon-Absorbing Layer [PCBM:MDMO-PPV] Substrate [Glass] Cathode [GaIn] Sealant / Adhesive Substrate [Glass] Conductive Film [ITO] Student - Measured OPV Parameters Interdigitated Source & Drain Electrodes Polymer Thin-Film Transistor (OTFT) Educational Topics [2,6]: Educational Topics [2,6]: - Transistor Device Physics - Charge Transport - Carrier Mobility - Charge Injection - Organic vs. Inorganic Transistor Operation Sealant / Adhesive Substrate [Glass] Conductive Film [ITO] Drain Electrode [ITO] Semiconducting Layer [P3HT] Insulating Layer [PVA] Substrate [Glass] Gate Electrode [GaIn] Source Electrode [ITO] Regioregular P3HT Substrate Gate Insulator Source Drain Organic Semiconductor -V D -V G + + + + + + Bottom-Gate OTFT showing path of charge carriers V GS = - 40 V V GS = - 30 V V GS = - 20 V Assessment & Laboratory Set-Up Acknowledgments References We are grateful for the financial support from the NSF (Grant No. 0633661). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF. We are also grateful for the support from the following experts serving on the advisory committee, sharing technical and pedagogical insights: National Science Foundation Dr. Gregory Crawford Univ of Notre Dame Dr. David Carroll Wake Forest Univ Dr. Ananth Dodabalapur Univ of Texas at Austin 1. I.-C. Khoo, Liquid Crystals, 2nd ed. (John Wiley & Sons, Inc., 2007), pp. 1 – 96. 2. J.M. Shaw and P.F. Seidler, IBM J. Res. & Dev. 45 (1), 3 – 9 (2001). 3. I.H. Campbell, B.K. Crone, and D.L. Smith, in Semiconducting Polymers: Chemistry, Physics and Engineering, 2nd ed., edited by G. Hadziioannou and G.G. Malliaras (Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, 2007), pp. 421 – 454. 4. Y. Kim et al, Nature Materials 5, 197 – 203 (2006). 5. G. Dennler, N.S. Sariciftci, and C.J. Brabec, in Semiconducting Polymers: Chemistry, Physics and Engineering, 2nd ed., edited by G. Hadziioannou and G.G. Malliaras (Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, 2007), pp. 455 – 530. 6. C.R. Newman et al, Chem. Mater. 16, 4436 – 4451 (2004). 7. Y.-H. Kim, D.-G. Moon, and J.-I. Han, IEEE Elec. Dev. Lett. 25 (10), (2004). Total Cost of Laboratory: US$9000 Initial Investment US$1000 Per 30 Student Operation 1: LCD 3: OPV 4: OTFT 2: OLED Rubbing Direction Mark (a) (b) (c) (d) (e) Alignment Polymer Electrode [ITO] Substrate [Glass] Spacer & Adhesive Mixture Flip and Slide Apart Space Created for Tapping Electrodes Fabrication Method Educational Topics [2,3]: Educational Topics [2,3]: - Lifetime of Organic Materials - Photometry / Radiometry - Polymer Science - Electroluminescence - Photoluminescence - Use of Optical Power Meters / Photodiodes DC Composite Student Survey Responses Composite Student Survey Responses (anonymous, 27 students) (anonymous, 27 students): Lab sessions contributed to mastery of course concepts (4.73 / 5.0) Lab facilities, equipment, supplies, etc. were adequate (4.69 / 5.0) The degree of lab diiculty was appropriate (4.66 / 5.0) Overall, the labs were effective learning experiences (4.70 / 5.0)