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Organic field‐effect transistors switched by insulated gates are the most essential building blocks, while usually plagued with degraded gate control arising from complicated dielectric engineering. Subsequently, the resulting large supply voltage and power consumption remain an essential issue for portable electronics driven by a single battery of only 1.5 V. Herein, wafer‐scale organic Schottky‐gate transistor arrays using inkjet‐printed few‐layer organic semiconducting crystals are reported. The transistors exhibit steep switching characteristics with an average subthreshold swing of 55 mV per dec and high signal amplification efficiency over 45 S A‐1, attributed to efficient Schottky gating and enhanced charge injection. Thereafter, high‐gain inverters are successfully demonstrated with an ultralow power consumption of only 800 pW; also, they are integrated as 1 V driven sequential logic circuits. A coplanar double‐gate geometry is also introduced for low‐voltage, single‐device AND logic. Therefore, the work opens new avenues toward the sustainable advancement in single‐battery‐driven, ultralow‐power organic electronics. [ABSTRACT FROM AUTHOR]

Narrow-band photodetectors based on halide perovskite have recently attracted significant attention due to their exceptional narrow-band detection performance and tunable absorption peaks covering a wide optical range. In this work, we report mixed-halide CH3NH3PbCl x Br3– x single crystal-based photodetectors have been fabricated, where the Cl/Br ratios were varied (3:0, 10:1, 5:1, 1:1, 1:7, 1:14 and 0:3). Vertical and parallel structures devices were fabricated which exhibited ultranarrow spectral responses under bottom illumination, with a full-width at half-maximum less than 16 nm. The observed performance can be ascribed to the unique carrier generation and extraction mechanisms within the single crystal under short and long wavelength of illumination. These findings offer valuable insights into the development of narrow-band photodetectors that do not necessitate the use of filters and hold tremendous potential for a diverse array of applications. [ABSTRACT FROM AUTHOR]

For a trap-free single layer single carrier (hole-only or electron-only) organic device of thickness d, dielectric constant εr, and mobility μ, the relation of current density j with voltage V is described by the well-known Mott–Gurney equation, j = 9 ε 0 ε r μ V 2 / 8 d 3 , which can be rewritten as j = G V , where G = 9 ε 0 ε r μ / 8 d 3 can be called space-charge limited (SCL) conductance. We investigated the current–voltage characteristics of vertical organic heterojunction phototransistors based on graphene as the source and C60/copper phthalocyanine (CuPc) heterojunction as the photoactive layer. We found that the drain current vs drain voltage (Id-Vd) characteristic is composed of two distinct SCL conductions with SCL-conductance being strongly dependent on the gate voltage and illumination intensity. At low gate voltages, the Id-Vd curve can be divided into two sections of SCL current conduction with different SCL-conductance: the lower conductance in the lower drain voltage range and the higher conductance in the higher drain voltage range. Both low and high SCL-conductance increase with the gate voltage and illumination intensity. However, as the gate voltage increases to a certain threshold, the two SCL sections unify to only one with the conductance being between them. Our findings implicate that the current conduction of an ideal vertical organic phototransistor (VOPT), whose source/organic interface contact is Ohmic and organic semiconductor is trap free, can be well modeled by the SCL conduction theory with carrier density dependent mobility, which is strongly related to the gate voltage and illumination intensity, and that the mobility of VOPTs at a certain gate voltage can be extracted by the Mott–Gurney equation. [ABSTRACT FROM AUTHOR]

Graphene–organic heterojunction phototransistors have great potential to achieve sensitive photoresponse owing to the excellent absorption of organic layers and fast charge transport in graphene. However, the photoresponse of most graphene‐based phototransistors is limited within visible light region with narrow bandwidth and poor sensitivity in the near‐infrared (NIR) region. Herein, a graphene–organic NIR phototransistor is fabricated by integrating an organic heterojunction layer composing of phthalocyanine molecules and fullerene C60 onto the graphene channel. The phototransistor exhibits a high photoresponsivity of 2.2 × 103 A W−1 under 850 nm irradiation with the power density of 35.4 mW cm−2 (Vds = 1 V). Meanwhile, a bidirectional photoresponse (both positive and negative) is obtained at different wavelength regions. Further studies indicate that the gate voltage enables to effectively tune the photoresponse in the wavelength range where PbPc has a significant optical absorption. Such a tunability of photoresponse is especially beneficial for the exploration of new functionalities in logic function devices. This work presents a feasible strategy to prepare graphene–organic heterojunction phototransistor with broadband photoresponse as well as sensitive and tunable bidirectional signals at NIR region. [ABSTRACT FROM AUTHOR]

As an important classification of photodetectors, broad spectral photodiodes are ubiquitous in the fields of industry and scientific research. Here, we reported a type of broad spectral organic–inorganic hybrid photodiodes (OIHPDs) based on planar-bulk heterojunction, which composed of 3,4,9,10-perylenetertracarboxylic dianhydride (PTCDA), copper phthalocyanine (CuPc) and fullerene (C60). In our research, the dark current of the OIHPD with 10 nm C60 film (10 nm-C60 OIHPD) was as low as 25.6 μA, which is about 63 times smaller than the dark current of the OIHPD without C60 film (C60-free OIHPD). It is considered that the significantly enhanced performance of 10 nm-C60 OIHPD is attributed to the introduction of the C60 film, which act as hole-blocking layer to reduce the dark current. And through the schematic energy level model combined with experimental measurements, the reason for the dark current change was well explained. Furthermore, the specific detectivity of 10 nm-C60 OIHPD was almost one order of magnitude larger than it of C60-free OIHPD, and a notable enhancement of over 1011 cm Hz1/2/W was obtained due to the fiercely reduced dark current. These results provide insights on how to improve the performance of organic photodiodes. [ABSTRACT FROM AUTHOR]

Narrow-band photodetectors based on halide perovskite have recently attracted significant attention due to their exceptional narrow-band detection performance and tunable absorption peaks covering a wide optical range. In this work, we report mixed-halide CH 3 NH 3 PbCl x Br 3- x single crystal-based photodetectors have been fabricated, where the Cl/Br ratios were varied (3:0, 10:1, 5:1, 1:1, 1:7, 1:14 and 0:3). Vertical and parallel structures devices were fabricated which exhibited ultranarrow spectral responses under bottom illumination, with a full-width at half-maximum less than 16 nm. The observed performance can be ascribed to the unique carrier generation and extraction mechanisms within the single crystal under short and long wavelength of illumination. These findings offer valuable insights into the development of narrow-band photodetectors that do not necessitate the use of filters and hold tremendous potential for a diverse array of applications., (© 2023 IOP Publishing Ltd.)