Materials for organic and hybrid inorganic/organic electronics

  • PDF / 1,736,343 Bytes
  • 11 Pages / 585 x 783 pts Page_size
  • 104 Downloads / 262 Views

DOWNLOAD

REPORT


field of unconventional electronics presents both new opportunities and scientific challenges for the semiconductor and electronics industries. 1–7 The challenges span multiple length scales and the continuum from hard to soft matter. This broad field encompasses both printed electronics and optically transparent, mechanically flexible electronics—properties not associated with conventional silicon technologies. The first technology aims at the fabrication of extremely low-cost electronic devices such as rf-id tags, “smart” cards, electronic paper, and backplane circuitry for diverse displays by high-throughput manufacture (e.g., roll-to-roll, as in newspaper printing). The second targets “invisible” devices such as transparent circuits and Tobin J. Marks, Northwestern University, Evanston, IL 60208, USA; [email protected]

1018

MRS BULLETIN • VOLUME 35 • DECEMBER 2010 • www.mrs.org/bulletin

monitors. Some near-term and more futuristic examples are illustrated in Figure 1. The essential component of all modern electronics is the thin-film transistor (TFT), which serves as a “valve” to modulate the flow of current. Figure 2 shows some typical TFT structures. The three essential TFT materials components are the contacts (source, drain, and gate electrodes), the semiconductor, and the gate dielectric.8,9 TFT and organic TFT (OTFT) performance is governed by key metrics of these materials. For the contacts, it is the electrical conductivity and work function; for the semiconductor, it is the sign and mobility (m) of the majority carriers and the energy of the molecular orbitals/bands that contain them; and for the gate dielectric, it is the dielectric constant (k), the insulating characteristics and

MATERIALS FOR ORGANIC AND HYBRID INORGANIC/ORGANIC ELECTRONICS

Transparent Monitors

Transparent Televisions

Heads-up Display

Windshield

Figure 1. Electronics based on optically transparent materials.

a

b

c

Figure 2. Typical thin-film transistor structures: (a) Top-contact/bottom-gate; (b) bottom-contact/bottom-gate; (c) bottom-contact/top-gate.

breakdown strength, and the layer thickness (d ). Unlike conventional silicon electronics, to achieve these materials characteristics, the components ideally should be deposited from solution (e.g., by gravure or inkjet printing or by stamping) and at sufficiently low temperatures (