Solution‐Processed Organic n‐Type Thin‐Film Transistors

Abstract

ExperimentalThe overall process of the combi-chem system adopted in the present investigation is described in more detail in our previous reports [11±17]. The Eu, Si, and Ca solutions were prepared by dissolving Eu 2 O 3 (0.1 mol), Si(C 2 H 5 O) 4 -(TEOS) (0.5 mol), and CaCO 3 (0.5 mol) in nitric acid. The Mg, Sr, Ba, and B solutions were prepared by dissolving Mg(NO 3 ) 2´6 H 2 O (0.5 mol), Sr(NO 3 ) 2 (0.5 mol), Ba(NO 3 ) 2 (0.25 mol), and H 3 BO 3 (0.5 mol) in deionized water. The appropriate amount of each solution was then injected into a 6 mL test tube array according to the composition table with the assistance of a computer programmed injection system (108 different compositions per generation were used). The solutions in the tubes were dried at 80 C for 24 h. At this stage gelation took place for those compositions that contained more than 0.3 mol of Si, but the others were simply dried. These samples were further dried at 600 C for 2 h. The dried samples were pulverized and collected in a specially designed ceramic container (given the name ªcombi-chemº container) and successively fired at 900 C for 2 h in an ambient atmosphere. The firing temperature was selected out of several other temperatures such as 900, 1000, 1100, and 1200 C in view of the average and maximum luminance value of the first generation. Some of the samples chosen among the library were removed from the combichem containers and examined by XRD and scanning electron microscopy (SEM) analyses. The emission spectra and the decay curves were monitored at 400 nm, which simulates an InGaN LED light source, with the samples being left in the combi-chem containers using a plate reader accessory attached to a Perkin Elmer LS50B spectrometer with a xenon flash lamp. The luminance was calculated by integrating the product of the emission spectrum and the standard visual spectral efficiency curve based on CIE (Commission Internationale de l'Eclairage) regulation [25].

Fabrication and characterization of solution-processed methanofullerene-based organic field-effect transistors

“…Our measured electron mobility is more than three orders higher than electron mobilities reported previously for PCBM-based OFETs with calcium ͑Ca͒ electrodes and poly͑4-vinyl phenol͒ ͑PVP͒ as a dielectric in a similar device configuration. 38 A better device performance was obtained after sealing and storing the devices under ambient conditions in their studies. A very recent study showed ambipolar transport in PCBM-based transistors with SiO 2 as a dielectric, having a specific device structure where the source-drain electrode is ring type.…”

Solution-Processed n-Type Organic Field-Effect Transistors With High on /off Current Ratios Based on Fullerene Derivatives

“…Mobility values from 0.18 to 0.9 cm 2 /Vs are already obtained with high ON/OFF ratios for the solutionprocessed p-type materials [10]- [13], although the n-type solution-processed OFETs are still lagging in performance. The solution-processed fullerene derivatives are known as promising candidates for n-type OFETs [14]- [21]. Mobility values of up to 0.01 cm 2 /Vs are already reported with the solutionprocessed phenyl-C61-butyric acid methyl ester (PCBM) in the bottom-contact (BC) configuration on SiO 2 [15] and in excess of 0.1 cm 2 /Vs with top-contact structure with polymer dielectrics [20].…”

Solution processible organic transistors and circuits based on a C70 methanofullerene

“…11 Recently, fabrication of organic transistors based on the solution processible methanofullerene ͓6,6͔-phenyl-C 61 -butyric acid methyl ester ͓͑60͔PCBM͒ has been reported. [22][23][24] Methanofullerenes possess an advantage over pristine fullerenes. Although their electronic properties are similar to those of unsubstituted fullerenes, i.e., they are characterized by relatively high electron mobility ͓1 ϫ 10 −2 -2ϫ 10 −1 cm 2 /V s ͑Refs.…”