Robust, high-performance n-type organic semiconductors

Abstract

Organic semiconductors (OSCs) are important active materials for the fabrication of next-generation organic-based electronics. However, the development of n-type OSCs lags behind that of p-type OSCs in terms of charge-carrier mobility and environmental stability. This is due to the absence of molecular designs that satisfy the requirements. The present study describes the design and synthesis of n-type OSCs based on challenging molecular features involving a π-electron core containing electronegative N atoms and substituents. The unique π-electron system simultaneously reinforces both electronic and structural interactions. The current n-type OSCs exhibit high electron mobilities with high reliability, atmospheric stability, and robustness against environmental and heat stresses and are superior to other existing n-type OSCs. This molecular design represents a rational strategy for the development of high-end organic-based electronics.

Electroless‐Plated Gold Contacts for High‐Performance, Low Contact Resistance Organic Thin Film Transistors

“…To verify this, a bottom‐gate top‐contact OTFT was fabricated using N , N′ ‐diphenethyl‐3,4,9,10‐benzo[ de ]isoquinolino[1,8‐ gh ]quinolinetetracarboxylic diimide (PhC 2 –BQQDI), a state‐of‐the‐art n‐type material which our group has recently developed. [ 49 ] PhC 2 –BQQDI is a solution‐processable, air‐stable semiconductor, which is thought to be able to withstand the entire process of the present transfer technique. The fabrication procedures were almost same as those for the p‐type OTFTs described above, although the preparation of the semiconductor and insulator layer was adjusted specifically to PhC 2 –BQQDI (see Experimental section).…”

Coherent Electron Transport in Air‐Stable, Printed Single‐Crystal Organic Semiconductor and Application to Megahertz Transistors

“…The device for gated Hall effect measurements was prepared according to the literature procedure. [ 31 ] A highly n ++ ‐doped Si wafer, serving as the gate electrode, with a thermally oxidized SiO 2 layer (200 nm) was encapsulated by an ≈30‐nm‐thick AL‐X601 layer for adjusting surface wettability and reducing trap sites. The SC PhC 2 −BQQDI thin film was deposited by edge‐casting [ 32 ] from a 0.03 wt% 1‐methylnaphthalene solution.…”

“…As estimated in our previous work, the direction of the transport measurement is along b *. [ 31 ] Therefore, the present transport properties are linked to band dispersion, which corresponds to the S − X line shown in Figure 2c. The effective mass ( m *) was estimated to be 2.09 m e , where m e is the rest mass of an electron.…”

“…Notably, organic SC FETs, which are composed of dense continuous channels, obey the ideal frequency response model for transistors, [ 14,19 ] unlike carbon nanotube FETs, which are extrinsically disturbed by parasitic capacitance due to inter‐tube discontinuities. [ 30 ] Very recently, our group reported a state‐of‐the‐art n‐type OSC, namely, N , N ′‐diphenethyl‐3,4,9,10‐benzo[ de ]isoquinolino[1,8‐ gh ]quinolinetetracarboxylic diimide (PhC 2 −BQQDI) [ 31 ] ( Figure a). PhC 2 −BQQDI was successfully applied to printed SC FETs, which exhibited a high electron mobility of 3 cm 2 V −1 s −1 in air, long‐term ambient air stability, and thermal durability up to >150 °C.…”

“…The crystal structure at 293 K was confirmed to involve 2D brickwork packing ( Figure a), which was consistent with our previous report. [ 31 ] The corresponding LUMO band structure was calculated in two dimensions by using the tight‐binding approximation. In PhC 2 −BQQDI, the bottom of the LUMO band was located around the S point (Figure 2b).…”