Suppressing bias stress degradation in high performance solution processed organic transistors operating in air

Abstract

Solution processed organic field effect transistors can become ubiquitous in flexible optoelectronics. While progress in material and device design has been astonishing, low environmental and operational stabilities remain longstanding problems obstructing their immediate deployment in real world applications. Here, we introduce a strategy to identify the most probable and severe degradation pathways in organic transistors and then implement a method to eliminate the main sources of instabilities. Real time monitoring of the energetic distribution and transformation of electronic trap states during device operation, in conjunction with simulations, revealed the nature of traps responsible for performance degradation. With this information, we designed the most efficient encapsulation strategy for each device type, which resulted in fabrication of high performance, environmentally and operationally stable small molecule and polymeric transistors with consistent mobility and unparalleled threshold voltage shifts as low as 0.1 V under the application of high bias stress in air.

Dynamic self-stabilization in the electronic and nanomechanical properties of an organic polymer semiconductor

“…2(c) ], suggests that two different processes occur during device aging. Indeed, the density of trap states (t-DOS) spectra confirm the presence of two regimes (see Supplementary Information Section 6 ) 18 , 27 . Molecular dynamics simulations on a C16-IDTBT amorphous morphology in the presence and absence of oxygen reveal no change in the donor-acceptor torsion distribution and so the charge transport properties along the polymer backbone are not affected by conformational effects due to the presence of oxygen (see Supplementary Information Section 7 ).…”

“…This is the smallest value ever reported for this polymer. Existing literature report sub-threshold swings that span a few V/decade, all the way up to 5 V/decade in C16-IDTBT transistors at room temperature 5 , 6 , 11 , 13 , 14 , 27 – 30 . After a month of ambient air exposure, textbook-like output characteristics are also observed.…”

High‐Performance Organic Electrochemical Transistors and Neuromorphic Devices Comprising Naphthalenediimide‐Dialkoxybithiazole Copolymers Bearing Glycol Ether Pendant Groups

“…[42] Moreover, it has been previously reported that water can introduce traps in organic semiconductors and hinder OFETs performance during operation. [43][44][45] The ionic liquid-1-ethyl-3-methylimidazolium bis(trifluorosulfonyl)imide (EMIM:TFSI)-is blended with poly(vinylidene fluoride-co-hexafluoropropylene) to prepare the ion gel solid electrolyte, as described in previous reports. [46] For ion gel gating we adopted a side gate architecture, which simplifies fabrication using lithography.…”

Organic single crystals of charge-transfer complexes: model systems for the study of donor/acceptor interactions

“…Trap states present at the edge of the HOMO and extending into the bandgap, which form due to various intrinsic and extrinsic factors such as structural defects, chemical impurities, energetic disorder, or environmental contaminants, result in charge localization and inhibit charge transport. [54][55][56][57][58] Therefore, in order to gain a complete picture of the electronic structure of both aand b-polymorphs, we accessed the energetic distribution of the density of trap states (t-DOS) in the bandgap of the two types of crystals using the Gru ¨newald method. 57,59,60 This method for t-DOS extraction is typically performed on unipolar semiconductors, as it requires the identification of a potential at which the channel is flat.…”

“…[54][55][56][57][58] Therefore, in order to gain a complete picture of the electronic structure of both aand b-polymorphs, we accessed the energetic distribution of the density of trap states (t-DOS) in the bandgap of the two types of crystals using the Gru ¨newald method. 57,59,60 This method for t-DOS extraction is typically performed on unipolar semiconductors, as it requires the identification of a potential at which the channel is flat. This condition does not always occur in ambipolar FETs, which may be always on, depending on the threshold voltages for holes and electrons relative to each other.…”