Trap healing and ultralow-noise Hall effect at the surface of organic semiconductors

Abstract

Fundamental studies of intrinsic charge transport properties of organic semiconductors are often hindered by charge traps associated with static disorder present even in optimized single-crystal devices. Here, we report a method of surface functionalization using an inert non-conjugated polymer, perfluoropolyether (PFPE), deposited at the surface of organic molecular crystals, which results in accumulation of mobile holes and a 'trap healing' effect at the crystal/PFPE interface. As a consequence, a remarkable ultralow-noise, trp-free conduction regime characterized by intrinsic mobility and transport anisotropy emerges in organic single crystals, and Hall effect measurements with an unprecedented signal-to-noise ratio are demonstrated. This general method to convert trap-dominated organic semiconductors to intrinsic systems may enable the determination of intrinsic transport parameters with high accuracy and make Hall effect measurements in molecular crystals ubiquitous.

Initial time-dependent current growth phenomenon in n-type organic transistors induced by interfacial dipole effects

“…The degradation phenomenon could be attributed to several charges trapped by high D it and long lifetime s it (Table II) PTCDI-C 13 channel enhanced by the dipole-induced field from the PI side chains (Fig. 1); this phenomenon suppressed gate field-induced traps [36][37][38] and intrinsic D it at the interface between PI and PTCDI-C 13 . When all dipoles within the PI film were parallel to the gate field, the accumulated carriers were saturated and the time-dependent I D simultaneously reached the maximum.…”

Charge transport calculations by a wave-packet dynamical approach using maximally localized Wannier functions based on density functional theory: Application to high-mobility organic semiconductors

“…Figure 6 shows the mobility as a function of temperature for several magnitudes of static disorder W from 0 to 100 meV. The intrinsic mobility of 192 cm 2 V −1 s −1 at 300 K is decreased to 75. as shown by the green bar [39,41,[44][45][46][47][48][49][50][51]. The temperaturedependent mobilities [12][13][14]52,53] also are plotted by green symbols.…”

Organic Single Crystals: An Essential Step to New Physics and Higher Performances of Optoelectronic Devices

“…) for both holes [ 7,18,21,35 ] and electrons; [ 27,36 ] (b) reproducible observation of a bandlike transport and intrinsic mobility anisotropy in a number of systems, [24][25][26][27][35][36][37][38] signifying that charge delocalization in van der Waals crystals is indeed possible, and the transport regime not dominated by static disorder can be achieved; (c) the discovery of new types of conducting and even metallic interfaces; [39][40][41] (d) observation of a long-range (1-10 µm) diffusion of mobile triplet excitons in high-quality organic crystals, as well as non-linear regimes in photoconductivity with nontrivial set of power exponents (1, 1/2, 1/3, and 1/4) due to singlet fi ssion, triplet fusion and interaction of mobile excitons with charge carriers; [28][29][30][31] (e) realization of ionic-liquid gated single-crystal devices; [ 42,43 ] (f) realization of solid-state ionizing radiation sensors based on solution-grown organic crystals; [44][45][46][47][48] (g) development of fl exible single-crystal devices suitable for the studies of electromechanical properties of organic semiconductors; [ 22,49,50 ] (h) realization of extremely high current density in organic light-emitting transistors; [ 51 ] (i) study of electrical magnetochiral anisotropy in a bulk chiral molecular conductor; [ 52 ] (j) elucidation of the role of dimensionality on Beatrice Fraboni received an MPhil in microelectronics from the University of Cambridge, UK, and a PhD in Physics from the University of Bologna, Italy. In 2000 she joined the Faculty of Physics at the University of Bologna where she is presently a professor in condensed matter physics.…”