Controllable band gap has been pursued to absorb a proper range of light by p-type absorber semiconductors for better performance photovoltaic devices. Here we introduce double substitutions with Cd and Cu for non-colloidal p-type PbS thin films to cover a broader range of optical band gap from 1.22 to 1.78 eV. Thin films of (Pb1-xCdx)1-yCuyS (x = 0-0.3 and y = 0-0.3) were grown by a single step chemical bath deposition process at a low temperature of 70 °C. The incorporation of Cd resulted in a wider band gap but changed the type of semiconductor into n-type above x = 0.2. Only the proper substitutions with both Cd and Cu induced an optimal band gap of 1.63 eV, which means a substantial improvement compared to 1.22 eV for pure PbS thin film, while maintaining p-type conductivity. Interestingly, excessive Cu substitutions beyond y = 0.2 inhibited crystallization significantly and generated an undesirably high carrier concentration.
Bibliographical noteFunding Information:
This work was financially supported by a grant of the National Research Foundation of Korea ( 2011-0020285 and 2013R1A2A2A01016711 ).
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All Science Journal Classification (ASJC) codes
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry