A Large Area Hybrid Phototransistor Platform with Large Detectivity and Fast Response to NIR Light

Abstract

Within multijunction organic and hybrid photodetectors (PDs), organic and hybrid phototransistors (HPTs) hold promises for high sensitivity (S) and specific detectivity (D*). However, it is difficult to achieve a trade-off between a large sensing area, a fast response, and a high D*. Here, we propose an alternative phototransistor concept relying on a geometrically engineered tri-channel (Tr-iC) architecture with a 4-mm² large sensing area, applied to a multilayer HPT whose active region is comprised of an inorganic In₂O₃/ZnO n-type field-effect channel and solution-processed organic bulk heterojunction (BHJ) or hybrid perovskite light-sensing layer. The resulting HPTs combine a responsivity (R) up to 10⁵ A/W, thanks to the efficient charge transport (at the bottom In₂O₃/ZnO layer) and a D* estimated at 10¹⁵Jones, which allows to measure low light power densities down to 10 nW cm⁻². These figures of merit are coupled to a fast response (risetime <10 ms and falltime of ≈100 ms for illumination, in the µW/cm² range), which is comparable to the time-response of organic PDs in a diode architecture. The experimental data are supported by a comprehensive device modeling, which helps highlighting the peculiar advantages of the proposed large area, Tr-iC, and multilayer HPT architecture.