A high-conductivity n-type polymeric ink for printed electronics

Abstract

Conducting polymers, such as the p-doped poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), have enabled the development of an array of opto- and bio-electronics devices. However, to make these technologies truly pervasive, stable and easily processable, n-doped conducting polymers are also needed. Despite major efforts, no n-type equivalents to the benchmark PEDOT:PSS exist to date. Here, we report on the development of poly(benzimidazobenzophenanthroline):poly(ethyleneimine) (BBL:PEI) as an ethanol-based n-type conductive ink. BBL:PEI thin films yield an n-type electrical conductivity reaching 8 S cm−1, along with excellent thermal, ambient, and solvent stability. This printable n-type mixed ion-electron conductor has several technological implications for realizing high-performance organic electronic devices, as demonstrated for organic thermoelectric generators with record high power output and n-type organic electrochemical transistors with a unique depletion mode of operation. BBL:PEI inks hold promise for the development of next-generation bioelectronics and wearable devices, in particular targeting novel functionality, efficiency, and power performance.

Influence of Molecular Weight on the Organic Electrochemical Transistor Performance of Ladder‐Type Conjugated Polymers

“…These significant changes in the electronic band structure of BBL upon electrochemical doping are comparable to those observed by chemical (molecular and polymeric) doping. [ 23,36 ] In addition, the formation of polaronic species in BBL 15 starts at voltage >0.2 V vs Ag/AgCl, while for BBL 60 , BBL 98 , and BBL 152 it starts already at a lower voltage (Figure 3e,f and Figure S10, Supporting Information).…”

“…This performance mismatch between p‐type and n‐type OECTs hinders the development of power‐efficient complementary devices/circuits, essential to many of the applications mentioned above. Several material and device design strategies, including introduction of oligo(ethylene glycol) side chains, [ 19 ] planarization/rigidification of the OMIEC polymer backbone, [ 20 ] modification of the source/drain electrode surface, [ 21 ] and use of molecular [ 22 ] or polymeric [ 23 ] dopants, are currently being explored. In the pioneering work by Giovannitti et al., [ 24 ] naphthalenediimide (NDI)‐based polymers were functionalized with oligo(ethylene glycol) side chains to yield n‐type OECTs with g m,norm = 0.1 S cm –1 and μC * = 0.1 F cm −1 V −1 s −1 .…”

Correlation between Transient Response and Neuromorphic Behavior in Organic Electrochemical Transistors

“…Moreover, this map provides rational design guidelines for neuromorphic devices by means of changing cation size and PEDOT content in the channel. We think that the discussion here would be valid in other depression mode devices other than PEDOT:PSS such as n‐type BBL:PEI [ 34 ] ; however, the contact resistance between source/drain electrodes and channel materials would play a significant role in a device at enhancement operation. This finding captures an interesting aspect of OECT physics and has significant ramifications for optimizing OECT‐based neuromorphic devices.…”

“…[27][28][29][30][31][32][33] In conjunction with the devices, the development of materials is also actively pursued to advance the field of OECTs, especially on the development of n-type materials. [34][35][36] The operation speed of OECTs, which has significant solutions, including LiCl, KCl, and CsCl. Typical output curves show that the drain current decreases upon applying a positive gate voltage consistent with the depletion-mode operation, arising from dedoping of PEDOT upon the injection of cations from the electrolyte.…”

High-throughput virtual screening for organic electronics: a comparative study of alternative strategies

“…The vision of employing organic materials as active components of electrical or optical devices, put forward and very actively pursued from the 80s 1 has been remarkably fruitful with a range of products that have reached the mass market, like organic light-emitting diodes (OLEDs), 2 prototype devices that approach their more established competitors, organic photovoltaic (OPV) devices, 3 and components of flexible electronic devices like conductive inks. 4 The field has been able to renew itself and identify new challenges, such as the development of novel emissive materials (dual emission, 5 room temperature phosphorescence, 6 thermally activated delayed fluorescence (TADF) 7 ), the exploitation of multiexcitonic states (singlet fission 8 (SF) and up-conversion 9 ) and the application into novel domains like organic bioelectronics, 10 neuromorphic 11 and quantum computing. 12 The premise for the successes and the optimism about the new challenges ahead is that organic materials for electronics can be fine-tuned with exquisite precision to have the desired electronic characteristics and the processing characteristics required for fabrication.…”