Highly Photosensitive Vertical Phototransistors Based on a Poly(3-hexylthiophene) and PbS Quantum Dot Layered Heterojunction

Abstract

We fabricated a vertical field effect phototransistor with Au/Ag nanowires as the transparent source electrode and with vertically stacked layers of poly(3-hexylthiophene) (120 nm) and lead sulfide quantum dots (380 nm), which formed heterojunctions. The built-in electric field in the layered heterojunction aids the separation of photoinduced excitons, while the short channel enables efficient carrier transport across the active region. Both of these benefits enable a high photoperformance and fast photoresponse. This vertical phototransistor can be operated at room temperature with a low operation voltage of −1 V and is therefore energy-efficient. Further, it has a wide response spectrum from 400 to 2100 nm, a high photoresponsivity of more than 9 × 10 4 AW −1 , and a high detectivity of up to 2 × 10 13 Jones (cm Hz 1/2 W −1 ) under infrared illumination. Additionally, this vertical phototransistor had a response time of 9 ms, which is faster than a previously reported lateral field effect phototransistor based on poly(3hexylthiophene)/lead sulfide quantum dots. The vertical architecture combined with the layered heterojunction approach provides a new, facile way of fabricating high performance devices.

A Broadband Phototransistor Based on Three-Dimensional Reduced Graphene Oxide Foam

“…The photocurrents excited by 405, 532, and 808 nm light are ~240, ~180, ~80 μA, respectively. Due to the different photoelectric conversion efficiency and the absorbance of different wavelengths, the photocurrent value is higher for shorter wavelengths than for longer ones, consistent with the absorption spectrum of the device, which is the usual case for phototransistors [ 37 , 38 , 39 , 40 , 41 ].…”

“…For the 3D rGOF photodetectors, photoresponsivity ( R ) is a key parameter [ 38 , 39 , 40 ]. Figure 3 displays the photoresponsivity ( R ) and photocurrent of the device at 532 nm as a function of laser irradiance Ee .…”

“…As soon as a hole reaches the drain, another hole replenishes the supply from the source. According to the photoconductive relaxation theory [ 18 , 40 ], the photoresponse current time of the 3D rGOF phototransistor can be well described by the Equation (3) and (4) for growth and decay, respectively. where I dark is the dark current, τ is the time constant, t is the response time when 532 nm laser is switched on and off, A is a scaling constants.…”

A Highly Sensitive UV–vis–NIR All‐Inorganic Perovskite Quantum Dot Phototransistor Based on a Layered Heterojunction

“…The decay time of the photodetector has previously been argued to be related with the carrier recombination time (lifetime, τ lifetime ) . The accumulation of electrons in the perovskite layer and the separation of electrons and holes by the thin DPP‐DTT film could hinder the recombination process and extend carrier lifetime . Similarly, the photocurrent decay trace can be also fitted using a biexponential function…”

Engineering Vacancies in Bi2S3yielding Sub‐Bandgap Photoresponse and Highly Sensitive Short‐Wave Infrared Photodetectors

“…2D Bi 2 S 3 nanosheets and colloidal quantum dots (CQDs) have also been developed . Although photodetectors based on Bi 2 S 3 nanomaterials have been reported, their performance is lower than commercial silicon detectors and recent‐emerging material platforms such as 2D materials, perovskite, and QD‐based hybrid photodetectors . For example, the Bi 2 S 3 nanorods and nanoflowers showed a photo‐switching ratio of only 23.6 .…”