ORaCEL encompasses several shared laboratories for research activities in organic electronics spanning Physics, Chemistry, Mechanical Engineering, Electrical Engineering, and Materials Science and Engineering, with a wide variety of processing and characterization equipment.
Film and Device Preparations
Glove Boxes (equipped with spin-coater and thermal vacuum evaporator) for fabrication and characterization of organic electronic devices
Nitrogen-filled glove boxes, equipped with a spin-coater, a metal/oxide/organic thermal vacuum evaporation system, as well as a photovoltaic characterization set up. An A.M. 1.5G simulated solar light is coupled into the glove box from an Oriel solar simulator (Oriel Sol3A Class AAA) to characterize the current-voltage characteristics of organic solar cells (OPVs). Similarly, the glove box OPV measurement system is capable of characterizing an external quantum efficiency of solar cells. There also glove boxes equipped with facilities for fabrication and testing of perovskite-based electronic devices, including solar cells and, spintronic devices.
Organic Molecular Beam Deposition
We operate two chambers for molecular beam deposition of organic molecules. Each is equipped with a turbo pump to facilitate molecular sublimation under pressure around 10^-7 Torr. The organic molecules are heated in a crucible wrapped by a tungsten wire that is powered by an external power source, while the desired substrate is positioned above the source. Flux is controlled by a manual shutter and monitored during deposition by a quartz crystal microbalance.
Blade Coating Facility
The blade coater is a fully automated setup that allows for coating organic materials from solutions. The setup includes:
- varying film casting speed,
- a coating stage integrated with a hot plate,
- a vacuum system for holding substrates in place,
- and adjustable blade height.
Wire Bar Coater
Wire-bar coating is quite similar with blade coating method. A wire-wound bar is a stainless steel rod around which stainless steel wire is tightly wrapped. Those wound wires create a thread which is always the same profile. Wire size is determined by the diameter of wire wrapped around the bar and it is a key parameter to determine the amount of coating solution by the open area. The eventual film coating thickness is dependent on bar height and deposition speed as well as solution concentration, viscosity and drying characteristics. This mini wire bar coater is manufactured by RK PrintCoat Instruments.
- Coating areas: up to 170 mm x 250 mm
- Standard coating speeds: 2 m/min – 15 m/min
- Wire diameter of the bar: > 4 μm
Asiga Max X 3D Printer
It is a UV stereolithography (SLA) 3D printer of high definition. A 385 nm light source crosslinks the resin material forming a solid part. A high definition projection system creates extremely fine 27 μm print resolution. A wide range of UV curable resins allows for many different use cases. This 3D printer is manufactured by Asiga.
- Material: resin
- Resolution: 27 μm
- Max Build Size: 51.8 mm × 29.2 mm × 75 mm
Dip Coater is to deposit layers of materials in a controlled and repeatable manner. The dip coating technique is a simple and versatile method for creating various coatings. Films of various thicknesses can be deposited from monolayers to multilayered structures. Automated dippers are well suited to situations when deposition is based on kinetic factors and where good control is needed.
- Dipping speed: 0.1 – 100 mm/min
- Sample substrate thickness: < 3 mm
- Sample height: < 140 mm
- Sample weight: < 150 g
Mini Slot Die Coater
Slot-die coating is one of the best techniques for scalable thin-film deposition compatible with both roll-to-roll and sheet-to-sheet deposition processes. Film thickness can be controlled by the ink concentration, flow rate and substrate speed. This mini slot die coater is manufactured by Ossila. The units are operable via the digital controls on the unit itself. The user can control over temperature, substrate speed and alignment, solution flow rate, channel thickness and head height.
- Slot die head width: 50 mm
- Shim thickness: 100 μm
- Stage Speed: 100 μm/s – 50 mm/s
- Syringe Speed: 12 μm/s – 5 mm/s
- Maximum coating length: 100 mm
- Maximum hotplate temperature: 120 °C.
Photovoltaic Characterization Facility
An A.M. 1.5G simulated solar light is coupled into the glove box from an Oriel solar simulator (Oriel Sol3A Class AAA) to characterize the current-voltage characteristics of organic solar cells (OPVs). The Oriel Sol3A simulators is certified to IEC 60904-9 Edition 2 (2007), JIS C 8912, and ASTM E 927-05 standards for Spectral Match, Non-Uniformity of Irradiance, and Temporal Instability of Irradiance. A Variable aperture accessory provides user the ability to vary the illumination without adjusting the power supply. The range of attenuation is infinitely variable from 0.1 – 1 Sun.
UV-Vis and Infrared Spectroscopy
Agilent UV-spectrophotometer from Varian is used for the ground state absorption measurement in the spectral range 200-1100 nm. Temperature dependent UV-Vis (77-393 K for solution samples and 293-393 K for thin film samples can be carried out using this set up.
The steady state photoluminescence (PL) spectra (77 K to room temperature) in the UV-NIR spectral are recorded using an Edinburgh Luminescence Spectrometer (Model: F900) equipped with a xenon lamp (Xe 900, xenon arc lamp that emits continuous radiation from 230 nm to 2600 nm). The samples can be excited with wavelength of interest and the emitted PL was detected using the photomultiplier tube (PMT). This set up can also be used to performed excitation dependence photoluminescence spectrum. We can measure the PL spectra from 400 nm to 1700 nm using this setup.
Two-Photon Photoelectron (2PPE) Spectroscopy
Time and angle resolved photoemission spectroscopy (trARPES) uniquely combines the power of ultrafast lasers and photoemission spectroscopy in order to directly probe the excited states and nonequilibrium dynamics of materials. A low energy ‘pump’ pulse first excites the electrons into an excited state, followed by a ‘probe’ pulse which ejects the electrons from the material for measurement. Delaying the pump pulse with respect to the probe allows us to see snap shots of the electrons as they decay back to the ground state. Our 2D CCD detector allows us to also view the momentum dependence of these states and the decay that follows. This technique gives us deep insight into the scattering mechanisms which takes place in materials, which helps us to understand the transport that takes place in devices.
All-in-one OPV and OLED Measurements (PAIOS)
Paios performs a large variety of electrical and optical characterizations on organic, perovskite and quantum-dot LEDs and solar cells with one click. Get consistent and precise measurement data, directly compare your results in the measurement software and speed up your
Compare the results from different devices directly in the software. Get highly consistent data.
Reliable and low-noise signals. High reproducibility.
Build a reproducible and reliable device database and store it in the Paios managing software.
Variable Angle Spectroscopic Ellipsometer
This ellipsometer is used to analyze thin film structural and optical properties including thickness, segregation character of multicomponent films, and complex refractive indices. The instrument is equipped with a deuterium and halogen lamp providing a large optical range from 193 nm to 1690 nm. The instrument is equipped with optional focusing probes with beam diameter of 300 mm. The system is also equipped with a custom heating stage and blade coater. The blade coater enables in-situ characterization of film properties during solidification from solution.
Figure. J. A. Woollam M2000 variable angle spectroscopic ellipsometer with (a) custom heating stage for in-situ measurement, and (b) blade coater setup.
Flash DSC – Flash Differential Scanning Calorimeter
Our TOLEDO’s Flash DSC is ideal for rapid-scanning. The instrument can analyze reorganization processes that were previously impossible to measure. The Flash DSC is the ideal complement to conventional DSC.
The ultra-high heating and cooling rates add a new dimension to the study of thermally induced physical transitions and chemical processes, for example, the crystallization and reorganization of polymers.
Discovery DSC from TA Instruments
- has a Fusion Cell™ with for unrivaled performance in baseline flatness, sensitivity, resolution, reproducibility, and reliability.
- provides exclusive T4P Tzero® heat flow technology for ultimate DSC performance and unique capability to conduct and store heat capacity measurements in a single run.
- has “app-style” touch screen puts instrument functionality simply One-Touch-Away.
- has reliable linear autosampler with programmable tray positions, most flexible programming of experiments, and automated calibration and verification routines.
- offers wide range of refrigerated cooling options .
- provides Tzero Press and Pans for fast, simple, and reproducible sample preparation.
X-ray Photo-electron Spectroscopy (XPS)
The Riber X-ray Photoelectron Spectroscopy instrument is a surface sensitive analysis tool which can measure the elemental and chemical composition of a sample. It measures the kinetic energy of photo-emitted core electrons from atoms ~5-10 nm deep which gives information about the bonding configuration of the near-surface atoms.Specifications
- Spot size: 2-3 mm diameter
- Sample size: 1 cm2
- Excitation source: Mg Kα (1253.6 eV)
- Detection limits: 0.1 – 1.0 %
- 5 slot sample holder
- Typical pump downtime ~ 2 hrs
- Resolution ~0.1 eV
Janis Probe Station for Charge Transport Measurements
A commercial probe station (Janis) with 4 independent micrometers for positioning needle probes inside a turbo-pumped high vacuum chamber is employed to characterize charge transport in organic films. The electrical probes are coupled to triaxial feedthroughs on an electrically isolatable cold stage. Cooling is provided by a cryogen-free Gifford-McMahon refrigerator and allows access to temperatures as low as 5K using only gaseous He.
Atomic Force Microscopy
Atomic Force Microscopy (AFM) data is acquired using the MFP-3D-BIO commercial instrument by Asylum Research. This instrument features a variety of scan modes, scan sizes of ~1 um up to 90 um, and can obtain sub-nanometer resolution both laterally and vertically. Scan modes
- Contact Mode Topography
- AC Air Topography (High-quality topography with minimum damage to “soft” materials)
- Conducting AFM (in-situ sample illumination coming soon)
- Electric Field Microscopy
- Magnetic Field Microscopy
- Scanning Kelvin Probe Microscopy (measures electrostatic potential on the surface)
1) Transient Pump Probe Spectroscopy
The pump beam at 1 KHz repetition rate (any wavelength from 270 nm to 3200 nm) is generated by a commercially available optical parametric amplifier pumped by a Ti:sapphire regenerative amplifier. Pulse laser excitation is then followed by a second broad band (350-1600 nm) generated in a CaF2 or sapphire or flint glass. A HELIOS transient absorption spectrometer is used for recording the dynamics of transient absorption spectra up to 6.8 ns with about 200 fs instrument response.
2) Time Resolved Second Harmonic Generation (TR-SHG) and Transient Pump probe Microscopy
TR-SHG experiments are performed using a Ti- Sapphire laser (250 KHz, 800 nm) to study interface properties. The output of regenerative amplifier is split into two beams: one as probe (800 nm) and the other to generate a tunable pump beam (500–750 nm) via optical parametric amplification. In addition this setup is used to perform pump probe in transmission and reflection (especially for devices) geometry as well as transient absorption microscopy.
3D Vector Superconducting Magnet and Optical System
This equipment system has the unique capability to control the temperature of a removable sample probe over a temperature range of T 1.8 K to T = 300 K with simultaneous control of a magnetic field. The variable field is controllable up to ±6.0 Tesla in the z-axis with a 1 Tesla spherical rotatable vector (at any degree). This equipment provides a unique platform for spin transport, spin Seebeck, spin transfer torque, photoluminescence, electroluminescence, and magneto-thermoelectrics in various magnetic materials and organic-based spintronic devices that we will be studying. The optical access in the magnet system enables us to perform the magneto-optical measurement as a function of magnetic field and temperature, providing a non-contact but sensitive approach for the magnetic characterization of the studied magnetic materials and organic spintronic devices that we will be studying.
The 2D FTS is performed using 1 KHz laser system unravel the electronic coupling between different resonances in the material. Dazzler pulse shaper is used in this experiment which can delay, filter, compress, split femtosecond pulses without losing coherence.
Home-built Sagnac Interferometer
The Sagnac Interferometer is a high-resolution optical instrument consisting of a high-field sweepable superconducting magnet, cryogenic system to cool the sample, and assorted optical components. In contrast to the conventional magneto-optical set up of which sensitivity is limited around µradians, it is used to measure the ultra-small angular rotation (with resolution as fine as 10 nano-radians) of linearly polarized light generated in various physical situations. Please see the figure 1 for the Sagnac Interferometer set up. Recently Sagnac Interferometer has been successfully applied to measure spin Seebeck effect in the ferromagnetic metal film (McLaughlin and Sun et al, Phys. Rev. B: Rapid Communications 95, 180401(R) (2017). ‘Editor’s suggestion’).
Cryogenic Ferromagnetic Resonance and Spin Transfer Torque FMR Measurement
Ferromagnetic resonance is a spectroscopic technique that takes advantage of the coupling between an RF signal traveling in the coplanar waveguide, and the magnetization of a sample sitting on top of the waveguide (see Figure 4). This is a set of accessory inserts for the Physical Property Measurement System (PPMS) facility that is located in the Department of Materials Science and Engineering. The equipment consists of two main instruments, namely the PPMS ferromagnetic resonance (FMR) Stand-alone CryoFMR probe, PhaseFMR spectrometer (PFMR) as well as PPMS Permute Box that allows electrical detection from the FMR probe. Both, the use of the PFMR and the CryoFMR technique require the presence of strong, fast sweepable magnetic fields, highly sophisticated Keysight microwave sources with tunable frequency in the centimeter wavelength range (9kHz to 20 GHz) as well a complex electronics for the control and data collection.