Investigation On Synthesis And Property Of Organic-inorganic Perovskites And Perovskites/Graphene Heterostructure

Two-dimensional materials show great potential in the applications of micro-optoelectronic devices, sensors and catalysis due to their unique properties. The rapid emergence of a new classic of organic-inorganic hybrid perovskites in 2009 gained large attention due to their desirable optoelectronic properties, simple preparation methods and low cost. The excellent performance of perovskites largely relies on the quality, therefore, a research on chemical vapor deposition synthesis of perovskites on different substrates and their optoelectronic properties are presented. Meanwhile, the heterostructure of perovskites/graphene is composed and the mechanical properties of the hetero-structure is discussed.Chemical vapor deposition and solution-vapor deposition were applied to prepare CH3NH3PbI3 and CH3NH3PbCl3, respectively, with a grain size of 10 ?m and thickness of 300 nm. Furthermore, a stable optoelectronic device based on CH3NH3PbI3 was fabricated. The effects of light illumination was investigated and the time-dependent photocurrent was recorded when the light turned on and off regularly. The optoelectronic study of the device shows that the photo-responsivity of the vapor-deposited CH3NH3PbI3 is 5.1 A/W under UV irradiation of 365 nm and a bias of 5 V. Quantum efficiency under the same condition is 2.5?103%, and response time is 3s, indicating organic-inorganic perovskites as promising materials for constructing high-performance photo-electronic devices.It is a primary method to rapidly gain access to high quality and few-layer graphene by exfoliating layered bulk crystals. Experiments were performed to identify the role of source crystal and the temperature and time of annealing during exfoliation. An area of 30 ?m monolayer graphene was exfoliated from high oriented pyrolitic graphite and the thickness was characterized by Raman and AFM, suggesting that mechanical exfoliation is an effective way to produce high quality and few-layer graphene. Meanwhile, the characteristic of Raman spectra of graphene with different number of layers was investigated.A vertically stacked heterostructure that consists of organic-inorganic perovskites from controlled vapor deposition and few-layer graphene from mechanical exfoliation was fabricated. AFM was used to quantify mechanical properties of the free-standing perovskites/graphene heterostructure. Young’s modulus of exfoliated few-layer graphene is about 0.88 TPa. With the deposition time ranging from 5 min to 20 min, the thickness of perovskites increases and the Young’s modulus of the heterostructure decreases from 0.73 TPa to 0.11 TPa.