Soft Lithography Technique In The Fabrication Of Rare Earth Luminescent Materials

The ordered arrays of luminescent YVO4:Eu3+ films with square (side length 19.17±2.05μm) and dot (diameter 11.20±1.82μm) patterns were fabricated by two kinds of soft lithography processes - microtransfer molding (μTM) and microcontact printing (μCP), respectively. Both soft lithography processes utilize the PDMS elastomeric mold as the stamp and combine the Pechini-type sol-gel process to produce the luminescent patterns on quartz plates, in which the YVO4:Eu3+ precursor solution was employed as ink. The ordered luminescent YVO4:Eu3+ patterns were revealed by optical microscope and their microstructure consisting of nano-scale particles was presented by scanning electronic microscope (SEM) observations. Additionally, the photoluminescence (PL) and cathodoluminescence (CL) spectra were carried out to characterize the patterned YVO4:Eu3+ samples. A strong red emission as a result of 5D0-7F2 transition of Eu3+ was observed under excitation of UV light or electronic beam, which implies that the scheme of combining the soft lithography methods with the Pechini-type sol-gel route has potential for fabricating the rare earth luminescent pixels for the next-generation field emission display devices.In this paper, we introduce YVO4:Eu3+ as an example for fabrication of the light-emitting arrays via soft lithography techniques combined with the Pechini-type sol-gel process. The square and dot patterns of YVO4:Eu3+ film on quartz plates were obtained by the facileμTM andμCP routes for the first time, respectively. The purpose that we design two types of experiments is to know if the popular soft lithography (μTM andμCP) can be used for the patterning of the inorganic rare earth salts. After we got a positive confirmation byμTM method, another extended attemptμCP method was proceeded to compare the ultimate results produced by both techniques. All experiments were performed with same stamps and precursors. The final patterns of YVO4:Eu3+ film arrays with a strong red luminescence made by both methods are different and their disparities have been clearly revealed by optical and fluorescence microscope (square arrays byμTM and dot arrays byμCP). The photoluminescence (PL) and cathodoluminescence (CL) spectra were carried out to characterize the corresponding samples. These results demonstrate that the Pechini-type sol-gel process has good compatibility with soft lithography techniques for patterning the inorganic phosphor materials, which has potential for fabricating the new-generation field emission display devices. We believe the results can guide us in the future research, and helpful to people who have interests in them.