Photoconductivity in reactively evaporated copper indium selenide thin films

Copper Indium Selenide (CIS) thin films were pulse electrodeposited at room temperature and at different duty cycles in the range of 6 – 50 %. Deposition current density was kept constant at 5 ma cm-2 in the present work. The total deposition time was 60 min. The precursors used were AR grade 0.3 M of each CuCl2 and InCl3, along with 0.2 M of SeO2. Thickness of the films estimated by Mitutoyo surface profilometer varied in the range of 0.8 to 1.2 μm with increase of duty cycle. XRD patterns of CIS films deposited at different duty cycles exhibit the chalcopyrite structure. Composition of the films indicated Cu/In ratio is greater than 1. Optical absorption studies indicated a direct energy band gap of 0.95 eV. Surface morphology of the films indicated that the grain size increased from 15 nm to 40 nm as the duty cycle increased. It is observed that as the duty cycle increases, the resistvity increases from 1.0 ohm cm to 10 ohm cm. The films were used as photoelectrodes in 0.5 M polysulphide redox electrolyte (0.5 M each Na2S, NaOH, S). At 60 mW cm-2, an open circuit voltage of 0.465 V and short circuit current density of 3.87 mA cm-2 were observed for the films deposited at 50 % duty cycle.

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Quantized electronic transitions in electrodeposited copper indium selenide nanocrystalline homojunctions

Scientific Reports ◽

10.1038/s41598-021-83526-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Shalini Menezes ◽

Anura P. Samantilleke ◽

Bryon W. Larson

Keyword(s):

Scale Up ◽

Indium Selenide ◽

State Density ◽

Single Step ◽

Copper Indium Selenide ◽

Ambient Atmosphere ◽

Inorganic Semiconductors ◽

3 Dimensional ◽

Roll To Roll ◽

Copper Indium

AbstractPairing semiconductors with electrochemical processing offers an untapped opportunity to create novel nanostructures for practical devices. Here we report the results of one such pairing: the in-situ formation of highly-doped, interface-matched, sharp nanocrystalline homojunctions (NHJs) with single step electrodeposition of two copper-indium-selenide (CISe) compounds on flexible foil. It produces a homogenous film, comprising inherently ordered, 3-dimensional interconnected network of pn-CISe NHJs. These CISe NHJs exhibit surprising non-linear emissions, quantized transitions, large carrier mobility, low trap-state-density, long carrier lifetime and possible up-conversion. They facilitate efficient separation of minority carriers, reduce recombination and essentially function like quantum materials. This approach mitigates the material issues and complex fabrication of incumbent nanoscale heterojunctions; it also overcomes the flexibility and scale-up challenges of conventional planar pn junctions. The self-stabilized CISe NHJ film can be roll-to-roll processed in ambient atmosphere, thus providing a promising platform for a range of optoelectronic technologies. This concept exemplified by CISe compounds can be adapted to create nano-scale pn junctions with other inorganic semiconductors.

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