Development of Smartkem’s OTFT Chemistry

Breakthrough Technology

 

The TRUFLEX® materials stack is a breakthrough technology comprising six individually designed material formulations covering every single layer in the device, starting from the initial OTFT base layer, all the way through to the final passivation layer chemistry. The ink set includes the active organic semiconductor formulation and a series of orthogonal passive interlayer inks (Base layer, Self-Assembled Monolayer, Organic Gate Insulator, Sputter Resistant Layer and Passivation layer). Smartkem’s proprietary materials set is covered by an extensive IP portfolio comprising 125 granted patents across 19 patent families and 40 codified trade secrets.

What makes TRUFLEX materials best in class?

 

The successful development of the TRUFLEX® materials set was due to Smartkem bringing together a team of scientists having the right skill sets and expert knowledge to design, develop and put into practice the best total technical solution in the field of organic electronics. The key skills required included organic chemistry, formulation chemistry, device physics and process engineering.

Driver ICs

 

If you were to use a direct wiring PCB based approach, the numbers of tracks required to connect to the LEDs are vastly different to the active matrix backplane. For instance, for 90,000 mini-LEDs, 180,000 connections plus a large number of ICs would be required. It is clear that using a TFT array for the backlight will significantly lower the cost of production for manufacturer.

Components of TRUFLEX® Organic Semiconductor Inks

 

Smartkem’s approach in developing the organic semiconductor formulations was to design a series of high mobility polycrystalline small molecule(s) that are combined with matched, high permittivity semiconducting oligomer(s). The benefits of this small molecule/oligomeric binder approach include:

 

  • Technical team has excellent understanding of formulations
  • In-depth knowledge of how to combine small molecule/polymer/additives to maximise the performance of OSC layer and the resulting oTFT
  • More than 50 years expertise relating to OSC formulation

1. High Mobility, Small molecule

  • Intrinsic mobility ≥ 20 cm2V-1s-1

2. Semiconducting polymer ‘controls’

  • Morphology of OSC layer
  • Phase segregation & uniformity of SM
  • Viscosity of ink

3. Solvents

  • Solubilise SM & Binder
  • Modify surface tension
  • Influence ink viscosity
  • Solvents for printing

TRUFLEX® technology advantages for printing

 

Smartkem’s technical approach of combining a high mobility polycrystalline small molecule with a matched semiconducting binder enables a wide formulation latitude and a wide range of printing methods. Rheology control of the ink is achieved through design of the chemistry of the binder, molecular weight selection/control and solids loading of the binder in ink Smartkem’s OSC materials are soluble in a range of low toxicity organic solvents enabling wide ink formulation latitude and providing for control of evaporation rate of a range of droplet sizes (tens of picolitres and below)