Ultrathin silica film derived with ultraviolet irradiation of perhydropolysilazane for high performance and low voltage organic transistor and inverter

Abstract

In recent years, organic electronic devices have become more and more popular, such as organic solar cell (OSC) [1][2][3][4], organic light emitting diode (OLED) [5][6][7] and organic thin film transistor (OTFT) [8][9][10][11] by virtue of their light weight, easy-processing and flexibility. As OTFT could be used as functional device or drive circuit to activate other devices [12,13], the development of OTFT becomes more urgent in practical applications. Low voltage operation as one of the major performances is very important to apply OTFT in low power consumption situations, especially in wearable and portable devices. As we all know, dielectric layer plays an important role to modulate the operation voltage of OTFT. Utilization of ultrathin dielectric film is an effective method to construct low voltage transistor. Therefore, new dielectric materials and novel processing methods for ultrathin dielectric films are two main ways to adjust the energy consumption performance of OTFT. Generally, most dielectric materials are composed of polymers or inorganic oxides [14,15]. For polymers, although the cheap and easy-process features make them popular in organic electronics [16,17], ultrathin polymer film has a risk of leakage. Inorganic oxides, such as silica and alumina, generally have excellent stability and low leakage even with ultrathin thickness, but they are usually prepared by physical vapor deposition (PVD) [18], chemical vapor deposition (CVD) [19], sol-gel [20] and atom layer deposition (ALD) [21], etc., which usually need high temperature, expensive equipment, and complex procedures. Therefore, from the standpoint of performance, preparation of ultrathin inorganic oxides layer through low cost and mild condition is highly meaningful for the construction of low voltage OTFT.Silica is one of the most extensively used inorganic dielectric oxides because of its high performance and mature processing [22][23][24][25]. However, the traditional processes are not compatible with modern organic electronics and large-scale production that generally requires low-cost and low temperature process. Recently, silica derived from solution precursor conversion method has drawn more and more attention. The most common solution precursor is perhydropolysilazane (PHPS) which possesses basic chemical structure of [-Si(H 2 )-NH-] and usually goes through the hydrolysis, condensation and oxidation reaction of active Si-N bond and Si-H bond to form silica [26][27][28][29][30][31][32]. In our previous work, the conversion is finished by thermal annealing of PHPS on a hot plate [33]. Despite lower power consumption method, it may be not completely compatible with organic electronics due to the thermal annealing procedure. Some polymer substrates with low glass transition temperature cannot endure the annealing temperature [34][35][36]. Therefore, we further exploit milder silica preparation method based on PHPS. In this letter, we introduce an ultraviolet irradiation conversion to fabricate ultrathin silica film and further appl...

Flexible Hard Coatings with Self-Evolution Behavior in a Low Earth Orbit Environment

“…Recently, perhydropolysilazane (PHPS), an inorganic polymer that consists of a Si–N skeleton and is free of organic groups, has demonstrated its superiority as a precursor for hard silica coating. − Due to its unique structure, PHPS can be converted into inorganic silica via a hydrolysis–condensation process assisted by heating or a photolysis–oxidation reaction induced by deep ultraviolet (DUV) light with a wavelength below 220 nm . This conversion condition is coincident with abundantly existing high-energy UV light in the LEO, which inspired us to utilize a UV and AO synergistic effect to obtain an inorganic silica coating from PHPS.…”

Self-assembled dipoles of o-carborane on gate oxide tuning charge carriers in organic field effect transistors

“…36,37 The value of C i allowed the OFETs to be operated with a gate voltage as low as 3 volts. 38 The electrostatic potential (U SAM ) of CBPA-and CDPAmodified AlO x was measured with Kelvin probe force microscopy (KPFM). Because KPFM measures the contact-potential difference between the surface and the probe tip, [39][40][41] quantitative determination of the electrostatic potential independent of tip requires using a surface reference, which was gold in this study.…”

Low-Voltage Organic Field-Effect Transistors: Challenges, Progress, and Prospects

“…Because commercialized high- k polymer materials are rare, research efforts have focused on downscaling the thickness . To acquire low-voltage OFETs, the thickness of low- k polymer dielectrics should be at least <100 nm, as summarized in Table . − Fabricating an ultrathin polymer gate insulating layer with a pinhole-free structure over large areas is very difficult .…”