High-performance Nonvolatile Organic Photoelectronic Transistor Memory Based on Bulk Heterojunction Structure

Abstract

Depending on the storage mechanisms, organic field-effect transistor (OFET) memory is usually divided into floating gate memory, ferroelectric memory, and polymer-electret-based memory. In this work, a new type of nonvolatile OFET memory is proposed by simply blending a p-type semiconductor and a n-type semiconductor without using an extra trapping layer. The results show that the memory window can be effectively modulated by the dopant concentration of the n-type semiconductor. With the addition of a 5% n-type semiconductor, blending devices exhibit a large memory window up to 57.7 V, an ON/OFF current ratio (I ON/I OFF) ≈ 105, and a charge retention time of over 10 years, which is comparable or even better than those of most of the traditional OFET memories. The discontinuous n-type semiconductor is set as a charge-trapping center for charge storage due to the quantum well-like organic heterojunctions. The generalization of this method is also investigated in other organic systems. Moreover, the blend devices are also applied to optical memory and show multilevel optical storage, which are further scaled up to 8 × 8 array to map up two-dimensional (2D) optical images with long-term retention and reprogramming characteristic. The results reveal that the novel system design has great potential application in the field of digital image memory and photoelectronic system.

Organic N-type Electrets for Field-effect Transistors, Photo Memories and Artificial Synapses

“…3f), indicating these electrons are efficiently transferred from C8-BTBT to degraded C8-PTCDI. This point is reasonable, and can be proved by referring to other systems 16 . Furthermore, Kelvin probe force microscopy (KPFM) was also used to investigate the process of charge transfer.…”

“…For clarity, we use a n-type semiconductor/p-type semiconductor (n/p) heterojunction architecture for OFETs application, while p-type semiconductor is 2,7-diocty [1]benzothieno [3,2-b] [1]benzothiophene (C8-BTBT). The photoresponsive behavior of OFETs is commonly realized by photo-induced charge transfer from donor into the acceptor [15][16] .…”

Polymer electrets and their applications

“…During the OFET operation, a high electric field induced across the polymer electret film caused a charge flow from the semiconductor channel toward the dielectric interface; the charges were mainly deposited in the organic side and the net charges in the polymer thus sever as the extra “gate” to shift the threshold voltage ( V t ) 186,187 . Nevertheless, it is still technically difficult to reduce the operating voltage without gate leakage in the polymer electret transistors for stable charge storage, because a higher programming voltage is required to generate a substantial shift of V t at room temperature yet avoid an impact of the reading voltage on it synchronously 188 . To this point, floating‐gate OFETs with the addition of Au nanoparticles in the gate electret layer (Figure 6(b)) are thus considered to realize organic flash memory devices (an on/off ratio >10 4 @V GS = 80 V) 189,190 .…”

Interface Modification in Three‐Terminal Organic Memory and Synaptic Device

“…First, three self-assembled molecules were designed with different hydrogen bonding. During the self-assembled operation in the solution, aggregates Modified the interface with self-doped nanostructures [19] OFET memory with Nanostructures WG 3 NS arrays [37] SAMs of aromatic amino compounds as the charge-storage layer [36] Morphology of the tunneling layer [38] OFET memory with the polymer electret and PCBM [40] Blending p-type semiconductor and n-type semiconductor [42] OFET memory with film and nanowire as the charge-storage layer respectively [44] Photomemory with perovskite/block copolymer [49] OFET memory with the donor-acceptor rod-coil diblock copolymers [48] Semiconductor layer, charge-storage layer and dielectric layer prepared with polymers [50] OFET memory with biodegradable chicken albumen gate insulator [51] OFET memory with the electrostatic interaction between APTES and rGo [57] SAMs including of the surface diploes [61] OFET memory with mixed SAMs [86] polymer materials based on cruciform SFXs [66] OFET memory using high dielectric constant polyimide electrets [67] OFET memory using ferroelectric fluoropolymer [74] OFET memory using BP and P(VDF-TrFE) [77] OFET memory using two-dimensional graphene and α-In 2 Se 3 [80] OFET memory using simple polymer blended dielectrics [85] The effect of surface energy on morphology and electrical properties of OFET [83] Enhance the charge density [88] OFET memory with donor/acceptor planarhetero junction interfaces [89] Reducing contact resistance by buffering the semiconductor/dielectric interface [90] Figure 3. The advances in the function of the interface in the three-terminal organic memory devices.…”

“…Meanwhile, the device showed good positive charge stability with its retention time reaching 1.5 × 10 5 s, which might result from the good hole transporting ability of the star-PTPMA. Lan et al [42] mixed the p-type semiconductor (IDTBT) and the n-type semiconductor (N2200) to fabricate a memory device, in which the p-type semiconductor acted as the charge channel layer and the n-type semiconductor as the charge capture unit. The storage performance of the device was enhanced with the increase of capture sites due to the bulk heterojunction formed by the two different semiconductors.…”