Ocean Optics miniature fiber optic spectrometers and thin film metrology instruments are beneficial for evaluating materials used in the testing and production of photovoltaic (PV) panels. The optical properties of solar materials are closely related to their effectiveness for use in PV panels and other solar installations.
As developers of PV materials seek improvement in solar cell efficiency and finished panel quality, the need is great for flexible systems to evaluate glass coatings, dopants and other PV materials. Optical sensing systems such as our UV-Vis and NIR spectrometers, thin film measurement systems and solar simulator testing units are easily configured for research lab and process line applications. Typical applications include characterization of solar cell materials, spectroradiometric measurement of solar simulators used in panel testing and quality control in panel production.
Example Setup: Photovoltaics Materials Measurement
A thin film on a substrate can act as an etalon, creating an interference pattern superimposed on the surface reflectivity when viewed in reflection. The spacing of the pattern’s sinusoidal peaks, when combined with the refraction index of the material, can be used to calculate the thickness of materials such as coatings used in photovoltaic panels.
Spectra observed in our operating software reveal oscillations caused by optical interference within the layers of the thin film substrate. Analysis of the wavelength position of the minima or maxima can determine the thin film’s thickness (with the known refractive index of the film) or its refractive index (with the known film thickness).
The HR2000+ES enhanced-sensitivity spectrometer is one of many options for reflectometry of thin films. The spectrometer is preconfigured with a wide-range grating set for ~200-1050 nm, a 10 µm slit and a detector collection lens for enhanced sensitivity. Also, the optical bench has a quartz window for UV transmission and the OFLV-200-1100 variable longpass order-sorting filter to eliminate second- and third-order effects.
A QR400-7-VIS-NIR reflection probe positioned at 90° to the sample measures specular reflectance from surfaces such as thin films. We couple our HL-2000 tungsten halogen light source to the probe for illumination and add a reflection probe holder and specular reflectance standard (not shown) to complete the sampling setup.
Alternatively, we can replace the probe holder and reflectance standard with a Single-point Reflection Stage and Si-SiO2 reference wafer (see illustration). STEP-WAFER reference standards are available in UV-VIS and VIS-NIR wavelengths, are 100 mm in diameter and are 5-step wafers with calibrated thickness ranges of 0-500 nm and 600-1100 nm.
OceanView spectroscopy software completes the system. If you select a thin film measurement system such as NanoCalc or SpecEl, standard and add-on software are available for thickness measurement, mapping functions, spectral simulation and more.
Photovoltaics Materials Measurement System Components
|HR2000+ES||High-resolution spectrometer with enhanced sensitivity is configured with an extended-range grating (200-1050 nm), 10 µm slit and variable longpass filter and quartz window (DET2B-200-1100)|
|HL-2000||Tungsten halogen light source (360-2400 nm)|
|QP400-7-UV-VIS||Premium-grade 400 µm diameter fiber optic reflection probe; 2 m length|
|Reflection probe fixture options||RPH-1 holds 0.25” (6.35 mm) diameter probes at 45° and 90° to the surface||STAGE Single-point Reflection Stage holds 0.25” (6.35 mm) diameter probes and accommodates substrates up 150 mm in diameter|
|Reference standard options||STAN-SSH high-reflectivity specular reflectance standard||STEP-WAFER options are Si-SiO2 reference wafers for thickness measurements of thin films on silicon wafers and other substrates|
|OceanView||Spectroscopy operating software|
UV-Vis and NIR spectroscopy are useful for validating the spectral output of solar simulators.
Thin film measurement techniques are utilized to characterize polymer solar cell materials.
The reflectivity of glass samples being considered for photovoltaic panels is a useful indicator of sample efficiency.