Influence of KCN treatment on CuInS2 thin films

Prog. Photovolt: Res. Appl.

et al. 2017

(Cd,Zn)S buffer layer and Zn1−xMgxO window layer were investigated to replace the traditional CdS buffer layer and ZnO window layer in Cu(In,Ga)(Se,S)2 (CIGSSe)‐based solar cell. (Cd,Zn)S with band‐gap energy (Eg) of approximately 2.6 eV was prepared by chemical bath deposition, and Zn1−xMgxO films with different [Mg]/([Mg] + [Zn]) ratios, x, were deposited by radio frequency magnetron co‐sputtering of ZnO and MgO. The estimated optical Eg of Zn1−xMgxO films is linearly enhanced from 3.3 eV for pure ZnO (x = 0) to 4.1 eV for Zn0.6Mg0.4O (x = 0.4). The quality of the Zn1−xMgxO films, implied by Urbach energy, is severely deteriorated when x is above 0.211. Moreover, the temperature‐dependent current density‐voltage characteristics of the CIGSSe solar cells were conducted for the investigation of the heterointerface recombination mechanism. The external quantum efficiency of the CIGSSe solar cell with the (Cd,Zn)S buffer layer/Zn1−xMgxO window layer is improved in the wavelength range of 320–520 nm. Therefore, a gain in short‐circuit current density up to about 5.7% was obtained, which is higher conversion efficiency of up to around 5.4% relative as compared with the solar cell with the traditional CdS buffer layer/ZnO window layer. The peak efficiency of 19.6% was demonstrated in CIGSSe solar cell with (Cd,Zn)S buffer layer and Zn1−xMgxO window layer, where x is optimized at 0.211. Copyright © 2017 John Wiley & Sons, Ltd.

Section: Methodsmentioning

confidence: 99%

Thin-film Cu(In,Ga)(Se,S)₂ -based solar cell with (Cd,Zn)S buffer layer and Zn_1−x Mg_x O window layer

Prog. Photovolt: Res. Appl.

et al. 2017

“…CIGSSe absorber layers were prepared by Solar Frontier K K by using a 2‐step process, where a sputter‐deposited Cu‐In‐Ga precursors were prepared and followed by selenizanition and sulfurization processes. It was reported that the solar cell with potassium cyanide (KCN) etching and the annealing treatment on the surface of the CIGS absorber layer demonstrates higher cell performances, especially open‐circuit voltage ( V OC ), than one without KCN etching and the annealing treatment . This is feasibly attributed to the removal of Cu x Se secondary phase located on the surface of the finished CIGSe films .…”

Section: Methodsmentioning

confidence: 99%

“…It was reported that the solar cell with potassium cyanide (KCN) etching and the annealing treatment on the surface of the CIGS absorber layer demonstrates higher cell performances, especially open‐circuit voltage ( V OC ), than one without KCN etching and the annealing treatment . This is feasibly attributed to the removal of Cu x Se secondary phase located on the surface of the finished CIGSe films . Therefore, KCN etching with 1 wt% for 1 minute and then annealing treatment at 250°C for 30 minutes in N 2 atmosphere were performed for the CIGSSe surface cleaning and modification after the deposition of the CIGSSe absorber layers.…”

Section: Methodsmentioning

confidence: 99%

Heterointerface recombination of Cu(In,Ga)(S,Se)₂‐based solar cells with different buffer layers

Progress in Photovoltaics

et al. 2017

Cu(In,Ga)(S,Se)2 solar cell is high conversion efficiency (η) thin‐film solar cell. One of the methods to further increase the η is to replace traditional CdS/ZnO buffer layers by more transparent materials to enhance carrier generation in spectral region from 330 to 550 nm. Cd0.75Zn0.25S/ZnO, thin CdS/ZnS(O,OH)/ZnO, and thin CdS/ZnS(O,OH)/Zn0.79Mg0.21O buffer layers are therefore developed to replace the traditional CdS/ZnO buffer layers in Cu(In,Ga)(S,Se)2‐based solar cells. ZnO, Zn0.79Mg0.21O, and ZnO:Al are prepared by sputtering method. Low‐surface carrier recombination, caused by low sputtering damage, is observed in the solar cells with CdS/ZnO or Cd0.75Zn0.25S/ZnO buffer layers, while the highest surface carrier recombination is presented in the solar cell with ZnS(O,OH)/ZnO buffer layer. Therefore, thin CdS/ZnS(O,OH)/ZnO or Zn0.79Mg0.21O buffer layers are applied in the solar cells to decrease surface recombination (reduced sputtering damage). Ultimately, conversion efficiencies of the solar cells with Cd0.75Zn0.25S/ZnO, thin CdS/ZnS(O,OH)/ZnO, and thin CdS/ZnS(O,OH)/Zn0.79Mg0.21O buffer layers are enhanced to 19.61, 18.60, and 18.81%, respectively, which are higher than that of 18.32% for the solar cell with the traditional CdS/ZnO buffer layers.

“…The CIGSSe absorbers were fabricated in the same deposition run for their same quality. In this work, the solar cell with potassium cyanide (KCN) etching and the annealing treatment after CIGSSe fabrication results in higher cell performances, especially V OC , than one without KCN etching and the annealing treatment, feasibly attributed to the removal of Cu x Se secondary phase located on the surface of the finished CIGSSe film . Consequently, KCN etching (1 wt% and 1 min) and then annealing treatment at 250°C for 30 minutes in N 2 atmosphere were conducted for the CIGSSe surface cleaning and modification after the preparation of the CIGSSe layer.…”

Section: Methodsmentioning

confidence: 99%

Aluminum‐doped Zn_1 − xMg_xO as transparent conductive oxide of Cu(In,Ga)(S,Se)₂‐based solar cell for minimizing surface carrier recombination

Progress in Photovoltaics

et al. 2017

A 19.5%-efficient Cu(In,Ga)(S,Se) 2 (CIGSSe)-based solar cell is obtained by replacing traditional CdS/ZnO buffer layers with Cd 0.75 Zn 0.25 S/Zn 0.79 Mg 0.21 O buffer layers for increasing short-circuit current density because band-gap energies of Cd 0.75 Zn 0.25 S and Zn 0.79 Mg 0.21 O are wider than those of CdS and ZnO, respectively. This yields the increase in external quantum efficiency in a short wavelength range of approximately 320 to 550 nm. Moreover, difference of conduction band minimum (E C ) between Zn 1 − x Mg x O:Al (transparent conductive oxide, TCO) layer