Investigation of valence plasmon excitations in GMZO thin film and their suitability for plasmon-enhanced buffer-less solar cells

• Published in: Solar energy 2019-01, Vol.178, p.114-124
• Main Authors: Garg, Vivek, Sengar, Brajendra S., Kumar, Amitesh, Siddharth, Gaurav, Kumar, Shailendra, Mukherjee, Shaibal
• Format: Article
• Language: English
• Subjects: Absorbers; Buffer layers; CIGSe; Circuits; Conduction; Conduction bands; Emission analysis; Emission measurements; Fabrication; Heterojunctions; Mathematical analysis; Metal oxides; Open circuit voltage; Parameter estimation; Performance prediction; Photoelectron spectroscopy; Photoelectrons; Photovoltaic cells; Plasmons; Scanning electron microscopy; Short circuit currents; Short-circuit current; Solar cells; Solar energy; Spectroellipsometry; Thickness; Thin films; Ultrathin solar cells; UPS
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2018.12.017

[Display omitted] •A novel approach to generate plasmons in GMZO thin film is reported.•Plasmon generation in GMZO is investigated using UPS, FESEM, and SE measurements.•Suitability of GMZO for buffer-less solar cells is probed using band-offset studies.•Devices performance parameters with varying band-offsets are theoretically estimated.•Using measured material and CBO parameters device performance is predicted. The approach of eliminating buffer layer in conjunction with plasmon-enhanced transparent conduction oxide (TCO) layer is an attractive methodology to realize low-cost ultrathin buffer-less solar cells (SCs) by introducing plasmon-enhanced absorption and reduced fabrication steps. Here, we report a novel method to generate wide-band sputter-stimulated plasmonic feature in Ga-doped-MgZnO (GMZO) thin-films, which are observed due to the different metallic and metal-oxide nanoclusters formation. Through an extensive analysis of photoelectron spectroscopy, spectroscopic ellipsometry, and field-emission scanning electron microscope measurements the evaluation of plasmonic features and correlation of them with various nanoclusters inside GMZO thin-film is performed. Additionally, the suitability and expected performance of plasmon-enhanced GMZO thin-film based buffer-less SCs are probed through; 1) band-offset analysis at the plasmon enhanced-GMZO/CIGSe heterojunction; 2) simulation studies to analyze the effect of conduction band-offset (CBO) on the performance of the buffer-less SCs; 3) predicting the performance of the buffer-less SC using the parameters of GMZO thin-films with varying CBO, and 4) envisaging the concept of ultrathin buffer-less SC with calculated CBO and absorber layer thickness (300 nm) for ultrathin SCs. Moreover, at the experimentally calculated band-offset with ultrathin absorber layer thickness (300 nm), theoretically calculated buffer-less SC performance parameters estimated to be open-circuit voltage (Voc): 0.75 V, short-circuit current density (Jsc): 17.29 mA/cm2, fill-factor (FF): 80.5%, and efficiency (Eff): 10.46%.