Solution-processable and photo-programmable logic gate realized by organic non-volatile floating-gate photomemory

Abstract

Programmable inverters using non-volatile floating-gate photomemories as basic building blocks instead of field-effect transistors enable the manipulation of threshold voltage by photons, providing an additional degree of freedom for applications in integrated circuits. However, the development of organic photo-controllable inverters is challenging due to issues such as solubility constraints for film stacking and the immaturity of photo-recordable devices. Notably, the development of organic non-volatile floating-gate photomemories (ONVFGPs) with n-type charge-transporting layers still lags behind that of the p-type layers due to the limited availability of suitable solution-processable charge-trapping materials and charge-transporting material pairs. Herein, photo-crosslinkable polystyrene-b-poly(methacrylic acid) (PS-b-PMAA)/5,10,15,20-tetraphenyl-21H,23H-porphine zinc (ZnTPP), which follows anti-Kasha's rule, is adopted as the charge-trapping layer for ONVFGPs. Both the second and first excited states of ZnTPP participate in photo-induced charge transfer, achieving the state-of-the-art photo-programming time of 0.1 second for ONVFGPs. The transfer curve of the derived photo-programmable inverter can be fine-tuned across a broad spectrum spanning from 405 nm to 830 nm, leading to at least six output states for the same input signal. This research confirms the possibility of integrated organic optoelectronics, opening avenues for solution-processable system-on-chip, neuromorphic computing and organic photonic integrated circuits.