Observation of correlated barrier hopping in blue luminescent PbI2 nanoparticles

• The dc conductivity of the samples increases with increasing temperature.
• The band gap of the sample enhanced over that of bulk lead iodide from 2.55 eV to 3.54 eV.
• The sample shows distinct blue light emission in the visible region at around 408 nm.
• Loss peak has been observed only at high temperature T=523 K.
• The calculated value of the ac activation energy is nearly the same as the dc activation energy.

Hexagonally shaped lead iodide nanoparticles were synthesized by a simple chemical route. Well crystallized nature of the sample was confirmed by X-ray diffraction patterns. Transmission electron microscopy shows that the particles are hexagonally shaped and the average particle size is estimated to be 16–18 nm. The band gap of the nanoparticles was found to be 3.54 eV. Photoluminescence spectra show some distinct blue light emission in the visible region around 408 nm. Mechanism of dc and ac transport was analyzed in the temperature range 298–523 K and in the frequency range 20 Hz–2 MHz. The activation energies are estimated from both dc and ac data and found to be in good agreement.

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