Real-time And In-situ Fluorescence Microscopy For Organic Thin-Film Growth: Method And System

In recent years, the organic thin film (OTF) optoelectronic devices show their great market prospects and development potential, and attract much attention from industry and science communities. Particularly, it is of great significance for building high-performance OTF optoelectronic devices to study the OTF growth structure characteristics, optimize growth conditions and further improve the quality of OTFs. Focusing on this important theme, a novel method to investigate the surface kinetics of OTF growth under ultra-high vacuum (UHV) environment using fluorescence microscopy was present in the thesis. Benefiting from the innovation of the thesis, the real-time OTF growth imaging monitoring and the real-time diffusion property of organic single molecules and molecular clusters on surface can be realized directly. The method not only can be used to study the growth kinetics of OTF on conductor and semiconductor substrates, but also can fill the gap of real-time in situ study of OTF growth on the insulator substrates. The achievements of the PhD work mainly include:1. A novel method of real-time in situ fluorescence microscopy for OTF growth was proposed on the basis of detailed description of organic molecular beam epitaxy and current research methods for OTF growth kinetics on surfaces. According to different subjects investigated, the method includes two techniques, one is real-time OTF growth imaging monitoring and the other is real-time single molecule tracking.2. An algorithm for deriving the OTF growth information from captured fluorescence images was presented. The real-time OTF growth imaging monitoring was achieved to evaluate the geometric morphology, growth velocity and uniformity by obtaining several growth data during the process of OTF growth, including the edge of islands, area, total fluorescence intensity, average intensity per pixel and so on.3. An efficient algorithm is presented to track the motion of single molecules fast and accurately, and single molecule localization is realized by image de-noising and applying a Gaussian mask algorithm which is inherited from Centroid, amd then the corresponding locations are linked into trajectories taking the characteristic intensity and actual displacement between subsequent frames into consideration. The method was quantitatively evaluated using simulated sequential images at variable signal to noise ratios (SNR). Compared with two-dimensional direct Gaussian fitting, the localization algorithm proposed here not only shortened the computational time to 1/10, but was also superior over the whole range of SNR yielding higher accuracy with nonameter resolution.3. An algorithm for deriving the OTF growth information from captured fluorescence images was presented. The real-time OTF growth imaging monitoring was achieved to evaluate the geometric morphology, growth velocity and flatness by obtaining several growth data during the process of OTF growth, including the edge of islands, area, total fluorescence intensity, average intensity per pixel and so on.4. A real-time in situ fluorescence microscopy system for investigating the OTF growth under UHV environment was firstly designed and developed. The system has a base pressure of 2×10-10mbar, enabling the control of the substrate temperature in a large range of 150K-450K precisely. Besides the essential equipments, like molecule evaporator and fluorescence microscopy, some other instruments, such as metal evaporator, electron/ion gun, reflection difference spectroscopy and ellipsometry are also integrated to achieve a variety of sample preparation, material modification and data analysis.5. The real-time fluorescence imaging monitoring of OTF growth on insulator substrate was achieved firstly by taking an example of p-6P growth on the Mica surface. The dynamic growth information of p-6P was conducted, revealing the quasi-one-dimensional growth mode of the p-6P molecules on the mica substrate.