Industrial Consultancy & Sponsored Research (IC&SR) , IIT Madras

Tailoring of Blue, Green, Green-red Emission from Inorganic Crystaline (Cd, Zn)se Quantum Dots – Znse Amorphous Phase Composite for White Light Application

Technology Category/Market

Category – Advanced Materials, Electronics and Circuits

Applications –Light Emitting Diodes, Quantum dots, Semiconductors, nanomaterials

Industry – Semiconductors

Market -The Quantum Dots Market size is expected to grow from USD 4.71 billion in 2023 to USD 10.51 billion by 2028, at a CAGR of 17.41% during the forecast period (2023-2028).


Problem Statement

  • QD-LEDs (Quantum Dot based Light Emitting Diode) has drawn intense research and commercialization due to narrow emission peak exhibited by QDs , better thermal stability and operation under high brightness and high current.
  • The existing technologies has disadvantages where QD-LEDs are susceptible to efficiency loss due to self-absorption, and broad deep level emissions where there are hurdles in controlling the ultra-small and stable QDs with uniform size distribution


  • The present invention discloses a (Cd,Zn)Se composite system for white light emission comprises a mixture of inorganic crystalline Zn alloyed CdSe quantum dot and ZnSe-amorphous (ZnSe-a) phase
  • The (Cd,Zn)Se composite system exhibits:
  1. A weakly confined sharp blue emission from ZnSe-a phase (ZS-NBE)
  2. A strongly confined size-tunable sharp near band-edge emission from (Cd,Zn)Se in the green to red region (CS-NBE)
  3. A broad defect deep level (DL) green-red emission;
  • The white light emission is achieved by tailoring the combination of weakly confined sharp blue emission from ZnSe-a phase and a broad green-red emission from deep defect level along with the near-band-edge emission from an alloyed QDs in (Cd,Zn)Se system.
  • The composite sizes of CdSe, Cd0.5 Zn0.5Se and Cd0.25   Zn0.75Se quantum dots are in the range of 2 to 5 nm
  • The intensity of broad DL emission drastically decreases with increasing particle size of quantum dot
  • The Zn-near-band-edge emission (Zn-NBE) is seen at 460 nm in all the spectra,the deep levels (DL) are seen at 640 nm in (a) and (b), and at 680 nm in (c)

Key Features/Value Proposition

Technical perspective

  • Light Emitting Device based on novel composite made of crystalline and amorphous inorganic semiconductor quantum dots, said composite comprising  Zn alloyed CdSe quantum dot and ZnSe-amorphous (ZnSe-a) phase used for white light applications
  • Emission of wide range of colour achieved by fine tuning/controlling the size and composition of Quantum dots

User perspective

  • Semiconductor Quantum Dots composite coated directly on UV light wide band gap metal oxide nanorods/ films or metal oxides
  • Low cost electroluminescence device
Questions about this Technology?

Contact for Licensing

Research Lab

Prof. Sudakar Chandran

Department of Physics

Intellectual Property

  • IITM IDF Ref. 1459
  • IN441213-Granted

Technology Readiness Level


Experimental proof of concept

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