Conjugated‐Polymer‐Based Lateral Heterostructures Defined by High‐Resolution Photolithography

Abstract

Solution processing of polymer semiconductors provides a new paradigm for large-area electronics manufacturing on fl exible substrates, but it also severely restricts the realization of interesting advanced device architectures, such as lateral heterostructures with defi ned interfaces, which are easily accessible with inorganic materials using photolithography. This is because polymer semiconductors degrade, swell, or dissolve during conventional photoresist processing. Here a versatile, high-resolution photolithographic method is demonstrated for patterning of polymer semiconductors and exemplify this with high-performance p-type and n-type fi eld-effect transistors (FETs) in both bottom-and top-gate architectures, as well as ambipolar light-emitting fi eld-effect transistors (LEFETs), in which the recombination zone can be pinned at a photolithographically defi ned lateral heterojunction between two semiconducting polymers. The technique therefore enables the realization of a broad range of novel device architectures while retaining optimum materials performance.

Programmable polymer light emitting transistors with ferroelectric polarization-enhanced channel current and light emission

“…The EL spectra with their emission maxima at $538 nm are characteristic of F8BT and in good agreement with earlier studies [4,12]. Using reported methods [11] we calculated the external quantum efficiency (EQE) of P(VDF-TrFE) and PTrFE transistors from the total photocurrent (detailed calculations are given in Section 2: Experimental). We obtained a maximum value of 1.06% and 0.16% for the P(VDF-TrFE) and PTrFE transistors, respectively.…”

“…tan(h) % h and cos(h) % 1Àh 2 /2, we can estimate the total photocurrent (I pÀtot ) from the measured photocurrent (I p ) by using the following relation: I pÀtot = (H/r) 2 Â I p . Finally the external quantum efficiency (EQE) was calculated from the total photocurrent (I pÀtot ) by using similar methods as previously reported [11], which in our case can be simplified to: EQE % 62.27 Â (I p /I D ). The calculated EQE values for the two transistors presented in Fig.…”

“…The light output of the LEFETs is yet too low for many practical applications. Several approaches have been proposed to increase the light output by using for instance bilayer structures composed of p-type and n-type semiconductors [6][7][8][9], organic heterostructures in the channel [10,11], improved injection of both carriers by tuning the work functions of injecting contacts [3,12], adding small amounts of semiconducting carbon nanotubes [13], incorporating optical structures [14,15] and multiple gates [16]. The drawback of these methods is that they add complexity to the fabrication process.…”

Photo‐patterning of Highly Efficient State‐of‐the‐Art Phosphorescent OLEDs Using Orthogonal Hydrofluoroethers

“…Finally, protective metal layers [23,24] or polymer films, such as Cytop [25] or parylene C [26] have been used to protect the organic semiconductor during conventional photolithographic processing. However, to the authors' knowledge, there are no reports to date on photolithographic patterning of OLEDs with state-of-the-art efficiency and lifetime.…”

Field-effect modulated Seebeck coefficient measurements in an organic polymer using a microfabricated on-chip architecture

“…15 We made sure that the patterned organic semiconductor bore no overlap with the heater so as to avoid crosstalk between the heater and the sensors. A 300 nm dielectric layer of PMMA was then spin-coated onto the chip and a 20 nm Au gate electrode was evaporated through a shadow mask.…”