A Novel Hybrid‐Layered Organic Phototransistor Enables Efficient Intermolecular Charge Transfer and Carrier Transport for Ultrasensitive Photodetection

Gao, Yong; Yi, Ya Sha; Wang, Xinwei; Meng, Hong; Lei, Dangyuan; Yu, Xue‐Feng; Chu, Paul K.; Li, Jia

doi:10.1002/adma.201900763

Cited by 107 publications

(89 citation statements)

References 51 publications

(63 reference statements)

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“…Further, 2 mg/mL and 5 mg/mL contents could also realize responsivity of 435.6 mA/W and 382.4 mA/W, respectively. By comparing the influence of 1 mW/cm 2 and 8 mW/cm 2 light intensities on the responsivity in detail, we obtained similar results to previous reports [13,14,15]; the value of responsivity decreased with the increase of light intensity, which indicated that the phototransistor fabricated by one-step spin-coating using the vertical phase separation method had good light detection performance. Figure 5d–f show the relationship between the detectivity of devices with gate voltage and light intensity, and it is clearly seen that the detectivity of the device reached the relatively large value of about 3.39 × 10 10 Jones.…”

Section: Resultssupporting

confidence: 88%

“…Compared to conventional photodiodes, phototransistors are controllable devices whose carrier density in the channel region can be tuned by the gate electrode, and therefore act as an in-built amplifier for enhancing the signal to noise ratio [2,11,12]. In recent years, investigations of phototransistors have mainly focused on the device structure design, fabrication process optimization, and material synthesis and selection, where the basic OTFT platforms are based on multiple layer structures [13,14,15,16]. The functional layers in the OTFTs, including electrodes, the dielectric layer, and semiconducting layers, are typically processed by thin film deposition techniques with a stacked layer-by-layer geometry [1,9].…”

Section: Introductionmentioning

confidence: 99%

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One-Step Coating Processed Phototransistors Enabled by Phase Separation of Semiconductor and Dielectric Blend Film

et al. 2019

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Fabrication of organic thin-film transistors (OTFTs) via high throughput solution process routes have attracted extensive attention. Herein, we report a simple one-step coating method for vertical phase separation of the poly(3-hexylthiophene-2,5-diyl) (P3HT) and poly(methyl methacrylate) (PMMA) blends as semiconducting and dielectric layers in OTFTs. These OTFTs can be used as phototransistors for ultraviolet (UV) light detection, where the phototransistors exhibited great photosensitivity of 597.6 mA/W and detectivity of 4.25 × 1010 Jones under 1 mW/cm2 UV light intensity. Studies of the electrical properties in these phototransistors suggested that optimized P3HT contents in the blend film can facilitate the improvement of film morphology, and therefore form optimized vertical phase separation of the PMMA and P3HT. These results indicate that the simple one-step fabrication method creates possibilities for realizing high throughput phototransistors with great photosensitivity.

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Section: Resultssupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

One-Step Coating Processed Phototransistors Enabled by Phase Separation of Semiconductor and Dielectric Blend Film

et al. 2019

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“…On the other hand, two published works have showed that forming an insulating wide-bandgap layer at the interface between the perovskite and charge transporting layers could effectively reduce the interfacial nonradiative losses 50,51 . There is also an example that demonstrates how to tackle interfacial losses by adding a layer of electron-blocking MoO 3 in-between the light absorber and the phototransistor 52 . We note that even in a type-II HJ-based perovskite quantum-dot/organic phototransistor, the photocarrier transfer could still benefit from the insulating ligands formed on the surfaces of the quantum dots 53 .…”

Section: Resultsmentioning

confidence: 99%

Deciphering photocarrier dynamics for tuneable high-performance perovskite-organic semiconductor heterojunction phototransistors

et al. 2019

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Looking beyond energy harvesting, metal-halide perovskites offer great opportunities to revolutionise large-area photodetection technologies due to their high absorption coefficients, long diffusion lengths, low trap densities and simple processability. However, successful extraction of photocarriers from perovskites and their conversion to electrical signals remain challenging due to the interdependency of photogain and dark current density. Here we report hybrid hetero-phototransistors by integrating perovskites with organic semiconductor transistor channels to form either “straddling-gap” type-I or “staggered-gap” type-II heterojunctions. Our results show that gradual transforming from type-II to type-I heterojunctions leads to increasing and tuneable photoresponsivity with high photogain. Importantly, with a preferential edge-on molecular orientation, the type-I heterostructure results in efficient photocarrier cycling through the channel. Additionally, we propose the use of a photo-inverter circuitry to assess the phototransistors’ functionality and amplification. Our study provides important insights into photocarrier dynamics and can help realise advanced device designs with “on-demand” optoelectronic properties.

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“…[ 1–4 ] By virtue of the additional gate terminal, organic phototransistors (OPTs), compared with their two‐terminal counterparts, enable easier modulation during light detection without issues such as increasing noise. [ 2,5 ] The photoresponsivity and sensitivity of the OPTs are continuously improved, while one outstanding issue is that these devices still suffer from slow response speed, which is detrimental to their application in emerging fields such as optical imaging and communication. [ 6,7 ] An essential approach for constructing OPTs is to form the planar heterojunctions, which is a critical structure for the separation of the strongly bound photogenerated excitons, [ 8,9 ] while the exciton diffusion still plays a critical role in the response speed of the OPTs.…”

Section: Introductionmentioning

confidence: 99%

Few‐Layer Organic Crystalline van der Waals Heterojunctions for Ultrafast UV Phototransistors

Guo

Jiang

Pei

et al. 2020

Adv Elect Materials

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Organic UV photodetectors using a transistor architecture can yield higher photoresponsivity than diode‐based devices because of the presence of a gate electrode. However, a long‐term issue of these phototransistor devices is the slow response speed, which hinders their practical applications. Here, organic UV phototransistors are constructed using few‐layer organic crystalline van der Waals (vdW) heterojunctions as the photoactive layers. The thickness of the photoactive layers is even less than the exciton diffusion length, thus removing the exciton‐diffusion bottleneck and giving rise to the confinement of charge separation and recombination within the adjacent molecular layers across the heterojunction interface. Hence, the phototransistor devices can exhibit a remarkably enhanced response speed (rise and decay times as short as only ≈4 and 6 ms, respectively). The layer‐dependent photoresponse characteristics are also observed, reinforcing the great importance of few‐layer organic heterostructures in phototransistor devices. This work not only provides a promising avenue toward fast response optoelectronic devices but also presents an in‐depth understanding on the microscopic nature of photogenerated charge carriers at the precision of molecular layers.

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A Novel Hybrid‐Layered Organic Phototransistor Enables Efficient Intermolecular Charge Transfer and Carrier Transport for Ultrasensitive Photodetection

Abstract: Scheme 1. a,b) Schematic structures of a layered OPT (a) and a hybrid OPT (b), and c) the general design of the HL-OPT.

Cited by 107 publications

References 51 publications

One-Step Coating Processed Phototransistors Enabled by Phase Separation of Semiconductor and Dielectric Blend Film

One-Step Coating Processed Phototransistors Enabled by Phase Separation of Semiconductor and Dielectric Blend Film

Deciphering photocarrier dynamics for tuneable high-performance perovskite-organic semiconductor heterojunction phototransistors

Few‐Layer Organic Crystalline van der Waals Heterojunctions for Ultrafast UV Phototransistors

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