Organic bipolar transistors

Wang, Shu‐Jen; Sawatzki, Michael; Darbandy, Ghader; Talnack, Felix; Vahland, Jörn; Malfois, Marc; Kloes, Alexander; Mannsfeld, Stefan C. B.; Kleemann, Hans; Leo, Karl

doi:10.1038/s41586-022-04837-4

Cited by 50 publications

(40 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[89][90][91] Through the appropriate design of organic molecules, we may achieve the carrier mobilities required for high switching speed transistors. [92,93] Larger exciton and carrier diffusion lengths are also of particular interest for solar cells and photodetectors. [94]…”

Section: Discussionmentioning

confidence: 99%

From Amorphous to Polycrystalline Rubrene: Charge Transport in Organic Semiconductors Paralleled with Silicon

Euvrard

Gunawan²,

Kahn

et al. 2022

Adv Funct Materials

View full text Add to dashboard Cite

While progress has been made in the design of organic semiconductors (OSCs) with improved transport properties, the understanding of the mechanisms involved is still limited, hindering further development. In this study, the interplay between structural order and transport considering one single OSC, analogous to past research on silicon is investigated. Rubrene (C42H28) is selected as it spans transport mechanisms from thermally activated hopping in its amorphous form to band‐like in highly ordered crystals in the orthorhombic polymorph. Transport characterizations including variable temperature conductivity, advanced Hall effect, and magnetoresistance measurements are performed on rubrene films with varying levels of order (polycrystalline vs amorphous), crystal phase (orthorhombic vs triclinic), and morphologies (platelet‐like vs spherulitic grains). A conductivity tuning range over four orders of magnitude between polycrystalline (platelet‐like) orthorhombic and amorphous films is reported. As observed in silicon, transport in polycrystalline orthorhombic rubrene is limited by energy barriers at grain boundaries. Additionally, a gradual transition from predominantly band‐like to predominantly hopping transport with increasing disorder, reminiscent of observations in silicon is shown. Nevertheless, OSCs differ from covalently bonded silicon by their weak intermolecular interaction. This study highlights that molecular packing must be optimized in OSCs to favor advantageous π‐orbital overlap and optimized transport properties.

show abstract

Section: Discussionmentioning

confidence: 99%

From Amorphous to Polycrystalline Rubrene: Charge Transport in Organic Semiconductors Paralleled with Silicon

Euvrard

Gunawan²,

Kahn

et al. 2022

Adv Funct Materials

View full text Add to dashboard Cite

show abstract

“…Organic semiconductors have been applied to various devices such as organic light-emitting diodes (OLEDs), organic thinfilm transistors (OTFTs), organic solar cells (OSCs), and organic semiconductor laser diodes (OSLDs). [1][2][3][4][5] Since barrier-free contacts for electrons and holes between organic semiconductors and electrodes are essential for efficient organic semiconductor devices, a cathode with a low work function (WF) and an anode organic semiconductors. The strategy is developed on the basis of the correlation of the HIL-dependent characteristics of OLEDs with the actual energy levels around anodes.…”

Section: Introductionmentioning

confidence: 99%

Unlocking the Full Potential of Electron‐Acceptor Molecules for Efficient and Stable Hole Injection

et al. 2023

View full text Add to dashboard Cite

Understanding the hole‐injection mechanism and improving the hole‐injection property are of pivotal importance in the future development of organic optoelectronic devices. Electron‐acceptor molecules with high electron affinity (EA) are widely used in electronic applications, such as hole injection and p‐doping. Although p‐doping has generally been studied in terms of matching the ionization energy (IE) of organic semiconductors with the EA of acceptor molecules, little is known about the effect of the EA of acceptor molecules on the hole‐injection property. In this work, the hole‐injection mechanism in devices is completely clarified, and a strategy to optimize the hole‐injection property of the acceptor molecule is developed. Efficient and stable hole injection is found to be possible even into materials with IEs as high as 5.8 eV by controlling the charged state of an acceptor molecule with an EA of about 5.0 eV. This excellent hole‐injection property enables direct hole injection into an emitting layer, realizing a pure blue organic light‐emitting diode with an extraordinarily low turn‐on voltage of 2.67 V, a power efficiency of 29 lm W−1, an external quantum efficiency of 28% and a Commission Internationale de l'Eclairage y coordinate of less than 0.10.

show abstract

“…Thus, alternative solutions would be required.Following recent developments in n-type OSCs, researchers have produced organic bipolar junction transistors (OBJTs). [13] While OBJTs may lead to faster switching speeds for wireless data, energy transmission, and may deliver high gain, the increase in processing steps would likely inflate manufacturing costs beyond limits of economic viability. Conversely, applications in biosensing rarely necessitate high cut-off frequency f T , as signals are often in the low Hz to kHz range.…”

mentioning

confidence: 99%

Extraordinarily Weak Temperature Dependence of the Drain Current in Small‐Molecule Schottky‐Contact‐Controlled Transistors through Active‐Layer and Contact Interplay

Bestelink

Teng

Zschieschang

et al. 2022

Adv Elect Materials

View full text Add to dashboard Cite

Low saturation voltages and extremely high intrinsic gain can be achieved in contact‐controlled thin‐film transistors (TFTs) with staggered device architecture, enabled by the energy barrier introduced at the source contact. The resulting device, the source‐gated transistor (SGT), is limited in its usefulness by the high temperature dependence of the drain current induced by the source energy barrier. Here, the interaction between the thermal characteristics of the source contact and the semiconductor to show drastically reduced temperature dependence for SGTs based on organic semiconductors (OSGTs) is exploited. This extraordinarily weak temperature dependence of the drain current is observed regardless of the height of the source energy barrier (27.8% in OSGTs with Ti contacts compared to 22.1% when using Au contacts, over a 34 K range). The reduction in mobility of the semiconductor offsets an increase in thermionic‐field emission of charge carriers at the source. This is a first for SGTs and provides a route to removing one of the last hurdles to their wider adoption. The OSGTs with Ti contacts also demonstrate: drain‐current saturation at very low drain‐source voltages (saturation factor of 0.22); noteworthy stability after 70 days; and minimal drain‐current variation with channel length or illumination.

show abstract

Organic bipolar transistors

Cited by 50 publications

References 41 publications

From Amorphous to Polycrystalline Rubrene: Charge Transport in Organic Semiconductors Paralleled with Silicon

From Amorphous to Polycrystalline Rubrene: Charge Transport in Organic Semiconductors Paralleled with Silicon

Unlocking the Full Potential of Electron‐Acceptor Molecules for Efficient and Stable Hole Injection

Extraordinarily Weak Temperature Dependence of the Drain Current in Small‐Molecule Schottky‐Contact‐Controlled Transistors through Active‐Layer and Contact Interplay

Contact Info

Product

Resources

About