Key Takeaways & Executive Findings
- •• A heterojunction photodetector based on CsPbBr3 QDs/CsPbBrxI3–x QDs was fabricated, achieving a type II band alignment that enhances carrier extraction and reduces non-radiative recombination. • By tuning the Br:I ratio, the band gap of CsPbBrxI3–x QDs was adjusted from 2.284 to 2.394 eV, enabling optimized energy level matching with the carbon electrode. • The optimized device with CsPbBr3 QDs/CsPbBr2I QDs heterostructure showed a 73% increase in responsivity and a specific detectivity improvement from 6.98 × 10^12 to 3.19 × 10^13 Jones. • The on/off ratio of the heterojunction photodetector reached 10^6, demonstrating significant performance enhancement over the pristine CsPbBr3 QDs device.
Abstract
All-inorganic CsPbBr3 perovskite quantum dots (QDs) have attracted extensive attention in photoelectric detection for their excellent photoelectric properties and stability. However, the CsPbBr3 quantum dot film exhibits a high non-radiative recombination rate, and the mismatch in energy levels with the carbon electrode weakens hole extraction efficiency. These reduces the device's performance. To improve this, a semiconductor photodetector based on fluorine-doped tin oxide (FTO)/dense titanium dioxide (c-TiO2)/mesoporous titanium dioxide (m-TiO2)/CsPbBr3 QDs/CsPbBrxI3–x (x = 2, 1.5, 1) QDs/C structure was studied. By adjusting the Br– : I– ratio, the synthesized CsPbBrxI3–x (x = 2, 1.5, 1) QDs showed an adjustable band gap width of 2.284−2.394 eV. And forming a type Ⅱ band structure with CsPbBr3 QDs, which reduced the valence band offset between the active layer and the carbon electrode, this promoted carrier extraction and reduced non-radiative recombination rate. Compared with the original device (the photosensitive layer is CsPbBr3 QDs), the performance of the photodetector based on the CsPbBr3 QDs/CsPbBr2I QDs heterostructure is significantly improved, the responsivity (R) increased by 73%, the specific detectivity rate (D*) increased from 6.98 × 1012 to 3.19 × 1013 Jones, the on/off ratio reached 106. This study provides a new idea for the development of semiconductor tandem detectors.
1. Introduction
In recent years, researchers have extensively investigated halide perovskite materials due to their unique photoelectric properties[1−5]. Among them, organic halide perovskite has been widely used in photodetectors, solar cells, and light-emitting diodes due to its tunable band gap, long diffusion length, and large absorption coefficient[6−8]. However, organic components are prone to degradation under water and oxygen conditions, destroying the structure, which leads to the lack of photoelectric properties and limits its further development[9].
In contrast, all-inorganic halide perovskite quantum dots (QDs) not only inherit the advantages of organic halide perovskite, such as adjustable band gap, high absorption coefficient, high carrier mobility, and long diffusion life[10, 11], but also show the advantages of QDs, such as high photoluminescence quantum yield, narrow half width and wide color gamut[12, 13]. Therefore, it has been widely studied by researchers[14−16]. However, the low conductivity of the perovskite QDs film limits the carrier extraction efficiency, and the device usually exhibits limited performance. It is still challenging to achieve high-sensitivity photodetectors using single junction photosensitive layer semiconductor.
There have been many studies on photosensitive layer heterojunction[17−27]. In 2022, Guan et al. develope...
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Chenguang Shen, Mengwei Chen, Wei Huang, Yingping Yang (2025). Research on heterojunction semiconductor photodetectors based on CsPbBr3 QDs/CsPbBrxI3–x QDs. SinoTechIntel Verified Research. https://doi.org/10.1088/1674-4926/25010022
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Frequently Asked Questions
What is the main improvement of the heterojunction photodetector compared to the original CsPbBr3 QDs device?
The heterojunction photodetector based on CsPbBr3 QDs/CsPbBr2I QDs shows a 73% increase in responsivity, a specific detectivity improvement from 6.98 × 10^12 to 3.19 × 10^13 Jones, and an on/off ratio reaching 10^6.
How is the band gap of CsPbBrxI3–x QDs tuned?
By adjusting the Br– : I– ratio during synthesis, the band gap of CsPbBrxI3–x QDs can be tuned from 2.284 to 2.394 eV.
What is the role of the type II band structure in the device?
The type II band structure formed between CsPbBr3 QDs and CsPbBrxI3–x QDs reduces the valence band offset with the carbon electrode, promoting carrier extraction and reducing non-radiative recombination.
What is the device structure of the studied photodetector?
The device structure is FTO/c-TiO2/m-TiO2/CsPbBr3 QDs/CsPbBrxI3–x QDs/C, where FTO is fluorine-doped tin oxide, c-TiO2 is dense titanium dioxide, and m-TiO2 is mesoporous titanium dioxide.
What is the significance of this study?
This study provides a new idea for the development of semiconductor tandem detectors by demonstrating the effectiveness of heterojunction engineering in improving photodetector performance.
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