Advances in Compact Modeling of Organic Field-Effect Transistors

Abstract

In this review, recent advances in compact modeling of organic field-effect transistors (OFETs) are presented. Despite the inherent strength for printed flexible electronics and the extremely aggressive research conducted over more than three decades, the OFET technology still seems to remain at a relatively low technological readiness level. Among various possible reasons for that, the lack of a standard compact model, which effectively bridges the device-and system-level development, is clearly one of the most critical issues. This paper broadly discusses the essential requirements, up-to-date progresses, and imminent challenges for the OFET compact device modeling toward a universal, physically valid, and applicable description of this fast-developing technology.

Identifying Key Transport Mechanisms in Organic Antiambipolar Transistors

“…Therefore, the widely observed non-linearity of a square-root I D versus V G plot can be properly modelled by adjusting the γ, with γ = 2 reserved for the ideal (trap-free) case. [18,19] Both of our devices were fitted to Equation (1) yielding a good overall agreement between theory and experiment (Figure 1b). In addition to the monotonous decrease in I D , the non-ideality of the transfer curve became more and more pronounced upon cooling both OFETs (Figure S1, Supporting Information), implying a substantial increase in γ at low T. Figure 1c shows the extracted γ as a function of 1/T.…”

Synergistic Effects of Self‐Assembled Monolayers in Solution‐Processed 6,13‐Bis(triisopropylsilylethynyl)Pentacene Transistors

“…The functional form of Eq. (2) assumes an exponential DOS near the edge of the transport orbital, [27] which is in our case the highest-occupied molecular orbital (HOMO). Such a trap DOS can be written (for E > E HOMO ) as (3) where N 0 is the base trap density at the HOMO edge, E-E HOMO is the energetic distance from the HOMO edge, k is the Boltzmann constant, and T c is the characteristic temperature dictating the energetic width of a given DOS (see the inset of Figure 3a).…”

“…[28] Note that this relationship is well-documented for an MTR or VRH model with an exponential DOS, by which the ratio between thermal energy (kT) and kT c dictates the rate of change in effective μ with respect to the total accumulated charge density, which in turn is directly proportional to V G -V T . [21,22,27] Figure 3a shows the calculated kT c for each of our OFET systems, where the data are arranged to visualize the increasing order of kT c (the lowest kT c means the case closest to the ideal disorder-free transport). We first note that the value of 46.6 meV from the OFET with the two SAMs compares favorably with that measured in the devices based on other benchmark p-type semiconductors, such as pentacene (5 0 meV), [29] poly(3-hexylthiophene (P3HT) (~50 meV), [30] and poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno [3,2-b]thiophene] (PBTTT) (~47 meV).…”

“…The functional form of Eq. (2) assumes an exponential DOS near the edge of the transport orbital, [27] which is in our case the highest‐occupied molecular orbital (HOMO). Such a trap DOS can be written (for E > E HOMO ) as…”

Bulk versus Contact Doping in Organic Semiconductors

“…After the successful commercialization of organic light-emitting diodes (OLEDs), other types of organic electronic devices are now poised to conquer the market, emphasizing the same merits of high multi-functionality, unconventional physical form factors, and additive, printing-based customizable manufacturing. The organic field-effect transistor (OFET) is one such emerging candidate [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ] that can play a key role in active-matrix displays, image sensors, and bio-neuromorphic systems.…”