Photodetectors with Quick Response For Optoelectronic Applications

Two-dimensional (2D) cadmium chalcogenide nanoplatelets (NPLs) exhibit unique optical properties and are applied in optoelectronics. In an article published in the journal ACS Applied Nano Materials, cadmium selenide (CdSe)/ cadmium sulfide (CdS) core/shell (CS) NPLs were synthesized to achieve photodetectors with quick response and high detectivity for optoelectronic applications.

Photodetectors with Quick Response For Optoelectronic Applications

Study: 2D CdSe/CdS Core–Shell Nanoplatelets for High-Performance Photodetectors. Image Credit: Wirestock Creators/Shutterstock.com

The effect of the reaction growth time on photophysical and structural properties, photodetection properties, and carrier dynamics of NPLs was highlighted. Rietveld refinement of X-ray diffraction (XRD) patterns of CdSe/CdS CS NPLs revealed the presence of zinc blende (ZB) and wurtzite (WZ) in the ratio of 5:3.

Increasing the growth time tuned the photoluminescence emission from green to red and enhanced the decay time by 12 times. The photodetector device based on CdSe/CdS CS NPLs showed a photo-to-dark current intensity ratio of approximately 600 with a photoresponse time of 100 milliseconds.

The maximum photoresponse of the NPLs observed in the visible region was approximately 113 milliamperes per watt with a high detectivity of about 2.1 x 1013 Jones. The results confirmed that the photodetectors based on CdSe/CdS CS NPLs were promising candidates for application in next-generation optoelectronics.

2D NPLs in Photodetectors

High-performing photodetectors are increasingly in demand to develop advanced photonic technologies for thermal imaging, biosensing, and optical communication. The p-n, Schottky, and hybrid organic−inorganic junctions in a photodetector help convert an optical signal into an electrical signal, recorded through an output. Here, the detectivity and photoresponsivity parameters determine the performance of a photodetector.

Solution-processed photodetector devices can meet the requirements in terms of cost, quality, low energy consumption, and stability of the photodetectors. On the other hand, the vapor-assisted deposition processing methods are unsuitable for the large-scale production of flexible photodetectors. Consequently, solution-processed techniques have great potential in next-generation photodetectors.

2D NPLs derived from II−VI semiconductor nanocrystals have been explored over the last decade. Due to their unique physical properties, 2D NPLs were applied in optoelectronic applications. Additionally, surface coating the NPLs with shell material having a wider band gap, including zinc sulfide (ZnS), Zinc selenide (ZnSe), and CdS can help resolve the issues of chemical stability and photostability occurring in pure NPLs.

Although deposition of ZnSe or CdSe or ZnS nanocrystals may cause lattice mismatch between shell and core materials, leading to interfacial strain, the lattice match is comparatively small when coated with CdSe/CdS core/shell (CS) NCs.

2D CdSe/CdS CS NPLs for High-Performance Photodetectors

In the present work, CdSe/CdS CS NPLs were synthesized at a high temperature and in a controlled manner using cadmium oleate and 1-octanethiol as cationic and anionic precursors, respectively. Here, the deposition of the CdS shell on the CdSe core was controlled by varying the amount of anionic precursor.

The CdSe/CdS CS NPLs synthesized previously via hot injection growth of the CdS shell generated a quasi-type-II band alignment, where the electrons and holes were delocalized in the shell and core, respectively. However, the controlled deposition of the CdS shell in the present work helped tune the photoluminescent emission from green to orange to bright red based on the varying thickness of the shell, useful for their sensing application in the photodetector.

Moreover, the deposition of the CdS shell on the CdSe core increased the number of active sites on the surface and reduced the surface trap states in CS heterostructures, enhancing the radiative decay channel and ultimately improving the photodetection performance of the device.

Furthermore, the reduced optical band gap owing to deposition of CdS layers helped in the photogeneration of charge carriers which were delocalized throughout CdSe/CdS CS NPLs/ The gradual CdS shell growth reduced the overlap between the electrons and hole wave function and increased the radiative lifetime of the CS NPLs, resulting in longer photoluminescence for imaging applications.

Femtosecond transient absorption (fs-TA) studies revealed that the bleach recovery kinetics were slower with continuous shell growth in the synthesized CS NPLs, enhancing optoelectronic devices’ efficiency.

Conclusion

Overall, CdSe/CdS CS NPLs were synthesized via a high-temperature shell growth approach. The ability to tune the steady-state absorption and photoluminescence of synthesized NPLs based on the reaction times made them promising candidates for optoelectronic applications.

The CdSe core deposited with the CdS shell passivated the surface trap states that suppressed the nonradiative pathway and enhanced the radiative decay channel. Additionally, fs-TA studies showed that CdS shell-deposited CdSe core NPLs had reduced bleach recovery dynamics.

Moreover, the fabricated CdSe/CdS CS NPLs exhibited fast response, high light-to-dark current intensity, and high detectivity. Thus, the CS NPLs serve as promising candidates for next-generation photodetectors in environmental sensing, safety, and security instruments.

Reference

Dutta, A., Medda, A., Ghosh, S., Sain, S., Patra, A. (2022). 2D CdSe/CdS Core–Shell Nanoplatelets for High-Performance Photodetectors. ACS Applied Nano Materialshttps://pubs.acs.org/doi/10.1021/acsanm.2c02663

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.

Bhavna Kaveti

Written by

Bhavna Kaveti

Bhavna Kaveti is a science writer based in Hyderabad, India. She has a Masters in Pharmaceutical Chemistry from Vellore Institute of Technology, India, and a Ph.D. in Organic and Medicinal Chemistry from Universidad de Guanajuato, Mexico. Her research work involved designing and synthesizing heterocycle-based bioactive molecules, where she had exposure to both multistep and multicomponent synthesis. During her doctoral studies, she worked on synthesizing various linked and fused heterocycle-based peptidomimetic molecules that are anticipated to have a bioactive potential for further functionalization. While working on her thesis and research papers, she explored her passion for scientific writing and communications.

Citations

Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Kaveti, Bhavna. (2022, August 11). Photodetectors with Quick Response For Optoelectronic Applications. AZoNano. Retrieved on April 12, 2024 from https://www.azonano.com/news.aspx?newsID=39545.

  • MLA

    Kaveti, Bhavna. "Photodetectors with Quick Response For Optoelectronic Applications". AZoNano. 12 April 2024. <https://www.azonano.com/news.aspx?newsID=39545>.

  • Chicago

    Kaveti, Bhavna. "Photodetectors with Quick Response For Optoelectronic Applications". AZoNano. https://www.azonano.com/news.aspx?newsID=39545. (accessed April 12, 2024).

  • Harvard

    Kaveti, Bhavna. 2022. Photodetectors with Quick Response For Optoelectronic Applications. AZoNano, viewed 12 April 2024, https://www.azonano.com/news.aspx?newsID=39545.

Tell Us What You Think

Do you have a review, update or anything you would like to add to this news story?

Leave your feedback
Your comment type
Submit

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.