Abstract
Titanium trisulphide (TiS3) has been widely used in the field of optoelectronics owing to its superb optical and electronic characteristics. In this work, a self-powered photodetector using bulk PbS/TiS3 p-n heterojunction is numerically investigated and analyzed by a Solar Cell Capacitance Simulator in one-Dimension (SCAPS-1D) software. The energy bands, electron-holes generation or recombination rate, current density-voltage (J-V), and spectral response properties have been investigated by SCAPS-1D. To improve the performance of photodetectors, the influence of thickness, shallow acceptor or donor density, and defect density are investigated. By optimization, the optimal thickness of the TiS3 layer and PbS layer are determined to be 2.5 μm and 700 nm, respectively. The density of the superior shallow acceptor (donor) is 1015 (1022) cm−3. High quality TiS3 film is required with the defect density of about 1014 cm−3. For the PbS layer, the maximum defect density is 1017 cm−3. As a result, the photodetector based on the heterojunction with optimal parameters exhibits a good photoresponse from 300 nm to 1300 nm. Under the air mass 1.5 global tilt (AM 1.5G) illuminations, the optimal short-circuit current reaches 35.57 mA/cm2 and the open circuit voltage is about 870 mV. The responsivity (R) and a detectivity (D*) of the simulated photodetector are 0.36 A W−1 and 3.9 × 1013 Jones, respectively. The simulation result provides a promising research direction to further broaden the TiS3-based optoelectronic device.
Highlights
Photodetectors that directly convert light into electrical signals have been developed for numerous applications, including medical diagnosis, aviation, target recognition, missile warning, and other fields [1,2,3,4,5,6,7]
Self-powered photodetectors which can realize light detection without an external power supply have aroused a great deal of interest
When the doping density of the PbS layer continually increased to 1017 cm−3, the overall performance of the photodetector including JSC, VOC, responsitivity, and detectivity were quenched enormously due to the increased carriers recombination, as shown in Figure S2 (Supporting Information)
Summary
Photodetectors that directly convert light into electrical signals have been developed for numerous applications, including medical diagnosis, aviation, target recognition, missile warning, and other fields [1,2,3,4,5,6,7]. The self-powered devices can work independently because of the photoelectric effect based on p–n or Schottky junction under illumination from light sources [8]. Photodetectors with self-powered behaviors based on p–n junction exhibit outstanding photoelectric performance, such as high response speed, large linear region, and low noise, and have achieved significant progresses [9]. The high responsivity and on/off ratio of the TiS3 /Si device were ascribed to the improvement in charge separation coming from the coupling effect of TiS3 nanoribbon and Si substrate [25]. The vertically grown TiS3 film with moderate S2 2− vacancies exhibits a long electron diffusion length for collecting electrons efficiently and an outstandingly high photocurrent density of 15.35 mA/cm was achieved at 1.4 V versus using reversible hydrogen electrode [27]. A self-powered PbS/TiS3 p–n heterojunction film photodetector is numerically investigated and analyzed by one-Dimension software SCAPS-1D.
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