Suppressing Dark Current in Organic Phototransistors through Modulating Electron Injection via a Deep Work Function Electrode

Organic phototransistors (OPTs) have been extensively investigated as photodetectors because of their internal photocurrent amplification. However, OPTs tend to show high dark current because they are derived at its ON state. Herein, we developed an OPT with low dark current by forming an injection barrier and suppressing the carrier injection in the dark. The dark current was reduced by over 4 orders of magnitude. The light-induced charge traps have maintained the responsivity at 42 mA W–1, consistent with the conventional OPTs. This low dark current OPT should expand the scope of OPT usage in practical electronic applications.