Construction And Application Of Linear Polarized Photoluminescence And Circular Polarized Photoluminescence Measurement System

Polarized light is widely used in daily life,and polarization measurement is also important in biological testing,medical treatment,environmental monitoring and industrial manufacturing.At present,there are many commercial instruments based on the principle of optical polarization measurement,and they have important applications in major fields.Most of the existing polarization measurement instruments use rotating polarizer or detector,which mainly measure the polarization of the luminous intensity of the sample,but less about the different polarization of different spectral bands in the spectrum.Meanwhile,conjugated polymer materials that can be used to make organic solar cells and OLED displays are widely concerned.In order to study the relationship between polymer morphology and photoluminescence polarization,we improve the design and build a Linear Polarization Photoluminescence measurement system and a Circular Polarization Photoluminescence measurement system,and polarization measurements were performed on polymer solutions and film samples.System design mainly includes optical path design and program design.The optical path design of the linearly polarized photoluminescence measurement system uses a rotating onehalf waveplate to change the angle of linearly polarized excitation light,measure the photoluminescence of the sample under different polarization angle excitation light,and obtain the photoluminescence polarization of the sample in the spectral range.The use of a linear optical path can prevent the polarization state of the measurement signal from being affected by reflection,and the optical path components and instruments are designed in detail.The program design uses the Lab VIEW virtual instrument work platform for visual programming,which has better support for system instruments.The system calibration results show that the anisotropy of the system components is very small,the system measurement error is 0.6%,and the linear polarization measurement system designed and built is reliable.The overall design of the circularly polarized photoluminescence measurement system uses a quarter-wave plate to convert the linearly polarized light after the polarizer into circularly polarized light for excitation of the sample to measure circularly polarized photoluminescence.The signal is collected by using a photoelastic modulator to modulate the sample signal,a grating monochromator to spectroscopy the measurement signal,and a lock-in amplifier to measure the difference between the left and right circularly polarized excitation signal.The system measurement program was designed and calibrated with the circularly polarized photoluminescence measurement system,and the system response was 80%,indicating that the system was working properly.Finally,the system was used to measure and study the thin film and solution samples of the polymer materials MEH-PPV and P3 HT,which were made into solution samples of different concentrations,different solvents and annealed thin film samples at different temperatures.The results show that the photoluminescence polarization of the solution samples is much higher than that of the thin films,and the photoluminescence polarization decreases with the increase of the solution concentration;in the same case,the photoluminescence polarization of the samples prepared with a good volatile solvent is slightly higher,and the physical mechanism of the existence of photoluminescence polarization of randomly oriented discrete polymer molecules is discussed by modeling;the surface crystallinity of the annealed thin film samples increases and the measured polarization increases.