Novel Organic Semiconductor BTQBT with High Conductivity and High Mobility

Abstract

We have found a novel organic semiconductor, BTQBT, with a high electrical conductivity of about 10 -3 S cm -1 and a high Hall mobility of about 3 cm2 V-1 s-1 at room temperature. We have also succeeded in measuring the temperature dependence of the Hall mobility. It varies with temperature as Τ-1 ·6 , which agrees with the theoretical Τ -1 '5 dependence for the mobility determined by lattice scattering. The characteristic transport property of BTQBT results from strong intermolecular interactions in the crystal, which is convinced by the energy dispersion with a bandwidth of about 0.5 eV from the theoretical and experimental band structures.

Ultrathin Organic Films Grown by Organic Molecular Beam Deposition and Related Techniques

“…This treatment was extended to other exciton systems found in a wide range of interesting neutral organic molecular and inorganic semiconductors (such as GaAs), suggesting that Wannier and CT excitons have a common physical origin which can be approximated by a hydrogenic wave function. This provides conclusive evidence that PTCDA and similarly close packed molecular compounds such as 192,193 BTQBT and possibly even C 60 and its analogs 259 form an important "transitional" class of materials that share many properties with both conventional semiconductors and insulator-like organic molecular crystals.…”

“…And since the molecular ion has finite size, shape, and orientation, the potential cannot be accurately modeled by a δ function. In addition, for planar stacking molecules such as PTCDA and BTQBT , where there is significant overlap between the π systems of adjacent molecules in the stack, the electronic states can no longer be considered as highly localized at a single lattice site. As a result, the exciton wave function must be a somewhat uncorrelated, extended state with considerable spatial coherence, and whose shape and symmetry is dependent on the crystalline and molecular structures …”

“…In the previous section, we have demonstrated that organic thin films can be controllably grown to dimensions of only a few monolayers. Hence, choosing archetype, extremely closely packed organic systems such as PTCDA or bis [1,2,5]thiadiazolo-pquinobis(1,3-dithiole) (BTQBT) [192][193][194] which might exhibit a developed and extended band structure, provides opportunities to study, for the first time, the nature of fundamental quantum excitations in OMCs using precision nanostructures. In this section we will provide a detailed review of such studies of PTCDA-based multilayers, along with conclusive experimental and theoretical evidence that fundamental optical excitations (called "excitons") can indeed be modified in certain nanostructured OMC systems characterized by a high degree of π-orbital overlap between adjacent molecules.…”

Heteroannulated acceptors based on benzothiadiazole

“…1), which forms single-component crystals that have high Hall charge-carrier mobility (3 cm 2 V À1 s À1 ). [69][70][71][72][73][74] In fact, the rst known isolated derivative of BBT was 4,8-bis(dicyanomethyl) derivative 11, which was obtained from two-electron reduction of BTDA-TCNQ and protonation of the stable, isolable disodium salt. 75 Indeed, in recent years the number of research articles on heteroannulated BT-containing materials has increased significantly, allowing an initial critical assessment of their properties and performance, which is the subject of this current review.…”

The Power of Packing: Metallization of an Organic Semiconductor

“…Variable temperature (VT) 4-probe single crystal measurements taken parallel (∥) and perpendicular (⊥) to the ab plane (Figure a) indicate significant anisotropy, with enhanced performance within the brick-wall arrays, resulting in σ RT (∥) = 1.0 × 10 –3 S cm –1 and E act (∥) = 0.14 eV, with σ RT (∥):σ RT (⊥) ∼ 50:1. This behavior may be compared to that of the donor–acceptor conductor bisthiadiazolo p -quino-bisdithiole (BTQBT) . To explore the response of both σ RT and E act of 5 to applied pressure, we performed high pressure (HP) 4-probe conductivity measurements over the range P = 0–12 GPa on a pressed pellet sample using a multianvil press.…”