Characterization of interface nature and band alignment in CBD-CdS/Cu(In,Ga)Se2 bi-layer structure by photoemission and inverse photoemission spectroscopy

Study of Band Alignment at CBD-CdS/Cu(In1-xGax)Se2 (x = 0.2 - 1.0) Interfaces by Photoemission and Inverse Photoemission Spectroscopy

“…One of the origins of this discrepancy between the expectation and the experiments is a saturation of open circuit voltage (V oc ) in the wide gap region, which is correlated with band alignment at p-n junction in the cell structure [7][8][9]. So, direct and independent determination of both of valence band and conduction band alignments is essential to clarify the electronic structure of the CBD-CdS/CIGS interfaces [11][12][13][14]. The CBD-CdS/CIGS interface is not an ideal system, where band gap would be easily modified by intermixing, compositional fluctuations and contaminations.…”

“…A serious degradation of the efficiency, however, has been observed in the wide gap CIGS. Therefore, characterization of the band alignments at the CdS/CIGS interfaces has been attempted by various techniques [10][11][12][13][14]. Therefore, characterization of the band alignments at the CdS/CIGS interfaces has been attempted by various techniques [10][11][12][13][14].…”

Properties of the Cu(In,Ga)Se2 absorbers deposited by electron-beam evaporation method for solar cells

“…However, they have still some problems such as a difficulty in the precise control of the evaporation source, the poor adhesion to a substrate and the use of harmful hydrogen selenide. In this study, we are going to suggest the electron-beam (E-beam) evaporation method using a Cu(In,Ga)Se 2 bulk compound as another promising candidate which offers significant advantages in terms of high directionality, stoichiometry and purity of the film [15,16].…”

Structure of chemically deposited Zn(S,O,OH) buffer layer and the effects on the performance of Cu(in,Ga)Se2 solar cell

“…The conduction band offset at the heterointerface changed from a spike-to a cliff-type depending on the ionization energy of the buffer layer material and composition of the CIGS layer, as demonstrated for the CdS/CIGS solar cells with the In/(Ga+In) molar ratio ranging from 0.20 to 0.40 [21]. Because it was difficult to estimate accurately the ionization energy of Zn(S,O,OH) layer before and after the removal of the Zn(OH) 2 layer because of the sensibility to the measuring atmosphere, the location of the Fermi level in the n-type semiconductor ZnO was estimated for the consideration by the following equation [22]: [23].…”