Tunable Light Response Modulated by the Organic Interface Charge Transfer Effect

Abstract

The combination of a donor (D) and an acceptor (A) is viewed as a promising approach to achieve high performance phototransistors, owing to their advantages in exciton dissociation and charge trapping. The electronic properties at the D‐A interface can vary substantially with the choice of materials, and how to precisely control the interface properties to achieve a controllable light response behavior is still an open question. Herein, a series of D‐A heterostructure is reported with varying electronic structures of the acceptor and demonstrate the ability to tune the performance and photocurrent decay behaviors. Two distinct types of charge transfer phenomena, ground state, and excited state charge transfer, are identified originating from the specific different energy level alignment and lead to the improved photoresponsivity up to 104 AW−1 and the significantly varied photosensitivity ranging from 102 to approaching 107. Furthermore, the distinct charge transfer scenarios elicit diverse temporal responses, encompassing both short‐term synaptic behavior as well as persistent memory characteristics. These findings shed light on the importance of understanding and controlling charge transfer property for phototransistor performance and applications. The ability to modulate the temporal responses opens up new possibilities for designing devices with desired memory and synaptic functionalities.

Recent progress of organic photonic synaptic transistors for artificial visual systems: structure configuration and innovative applications

“…62 The single-layer device structure has advantages in revealing the mechanism of synaptic transistor devices, which lays the foundation for the development of multifunctional synaptic devices and the construction of multi-field coordinated regulation synaptic transistors by combining with dielectric layers or interfaces with excellent charge capture/de-capture capabilities. 63…”

Solution treatment controls charge-transfer states and energy-level alignment at hybrid CuSCN-organic interfaces

“…10,15,16 Consequently, CuSCN has so far been successfully applied as hole transporting material in organic light-emitting diodes (OLEDs), 17,18 thin film transistors (TFTs), 10 and photovoltaic devices. [19][20][21] In contrast to inorganic-organic interfaces, efficient CT state formation is frequently observed at the donor-acceptor interface in organic photovoltaics [22][23][24] and the dielectric medium plays an important role in this process. 25 In general, electrostatically bound organic semiconductors have much lower dielectric constants (2)(3) than chemically bound inorganic semiconductors (10)(11)(12)(13)(14)(15), which results in localized Frenkel excitons rather than delocalized Wannier-Mott excitons.…”

“…In contrast to inorganic–organic interfaces, efficient CT state formation is frequently observed at the donor–acceptor interface in organic photovoltaics 22–24 and the dielectric medium plays an important role in this process. 25 In general, electrostatically bound organic semiconductors have much lower dielectric constants (2–3) than chemically bound inorganic semiconductors (10–15), which results in localized Frenkel excitons rather than delocalized Wannier–Mott excitons.…”