Effect of the Concentration of Complexing Agent on the Formation of ZnS Buffer Layer by CBD Method

CBD 방법에 의한 ZnS 버퍼층 형성의 착화제 농도에 따른 영향

  • Kwon, Sang Jik (Department of Electronics Engineering, Gachon University) ;
  • Yoo, In Sang (Department of Chemical and Biological Engineering, Gachon University)
  • 권상직 (가천대학교 전자공학과) ;
  • 유인상 (가천대학교 화공생명공학과)
  • Received : 2017.07.20
  • Accepted : 2017.09.01
  • Published : 2017.10.01


ZnS was chemically deposited as a buffer layer alternative to CdS, for use as a Cd-free buffer layer in $Cu(In_{1-x}Ga_x)Se_2$ (CIGS) solar cells. The deposition of a thin film of ZnS was carried out by chemical bath deposition, following which the structural and optical properties of the ZnS layer were studied. For the experiments, zinc sulfate hepta-hydrate ($ZnSO_4{\cdot}7H_2O$), thiourea ($SC(NH_2)_2$), and ammonia ($NH_4OH$) were used as the reacting agents. The mole concentrations of $ZnSO_4$ and $SC(NH_2)_2$ were fixed at 0.03 M and 0.8 M, respectively, while that of ammonia, which acts as a complexing agent, was varied from 0.3 M to 3.5 M. By varying the mole concentration of ammonia, optimal values for parameters like optical transmission, deposition rate, and surface morphology were determined. For the fixed mole concentrations of $0.03M\;ZnSO_4{\cdot}7H_2O$ and $0.8M\;SC(NH_2)_2$, it was established that 3.0 M of ammonia could provide optimal values of the deposition rate (5.5 nm/min), average optical transmittance (81%), and energy band gap (3.81 eV), rendering the chemically deposited ZnS suitable for use as a Cd-free buffer layer in CIGS solar cells.


Supported by : 한국 연구재단, 산업통상자원부


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