Organic Imager on Readout Backplane Based on TFTs With Cross-Linkable Dielectrics

We report on the fabrication of imagers based on organic semiconductors both in the photodiode layer and in the readout backplane. The photodiode is based on evaporated ultrathin (<;100 nm) stack of SubPc/C₆₀, sensitive in the wavelength range between 300 and 650 nm. The readout circuit is a switch matrix fabricated with a solution processed semiconductor (XPRD30B01) and two solution processed, crosslinkable dielectrics (XDRD30B01). The readout TFTs (140/5-μm channel width/length, respectively) have leakage current lower than 1 pA with the ON-current higher than 0.1 μA. The 32 × 32 pixel imagers with pixel pitch down to 200 μm are demonstrated with mean dark signal of a few μA/cm² and linear photoresponse up to the incident power of 100 μW. These results show feasibility of fabricating readout circuits with TFTs based on crosslinkable dielectrics. This enables reduction of two patterning steps (opening of the gate dielectric and of the encapsulation layer) to just photolithography, leading to simplification of the backplane manufacturing process.