Structural defects such as voids and compositional inhomogeneities may affect the performance of Cu(In,Ga)Se2 (CIGS) solar cells. We analyzed the morphology and elemental distributions in co-evaporated CIGS thin films at the different stages of the CIGS growth by energy-dispersive x-ray spectroscopy in a transmission electron microscope. Accumulation of Cu-Se phases was found at crevices and at grain boundaries after the Cu-rich intermediate stage of the CIGS deposition sequence. It was found, that voids are caused by Cu out-diffusion from crevices and GBs during the final deposition stage. The Cu inhomogeneities lead to non-uniform diffusivities of In and Ga, resulting in lateral inhomogeneities of the In and Ga distribution. Two and three-dimensional simulations were used to investigate the impact of the inhomogeneities and voids on the solar cell performance. A significant impact of voids was found, indicating that the unpassivated voids reduce the open-circuit voltage and fill factor due to the introduction of free surfaces with high recombination velocities close to the CIGS/CdS junction. We thus suggest that voids, and possibly inhomogeneities, limit the efficiency of solar cells based on three-stage co-evaporated CIGS thin films. Passivation of the voids’ internal surface may reduce their detrimental effects.

Voids and compositional inhomogeneities in Cu(In,Ga)Se2 thin films: evolution during growth and impact on solar cell performance / Avancini, Enrico; Keller, Debora; Carron, Romain; Arroyo-Rojas Dasilva, Yadira; Erni, Rolf; Priebe, Agnieszka; Di Napoli, Simone; Carrisi, Martina; Sozzi, Giovanna; Menozzi, Roberto; Fu, Fan; Buecheler, Stephan; Tiwari, Ayodhya N.. - In: SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS. - ISSN 1468-6996. - 19:1(2018), pp. 871-882. [10.1080/14686996.2018.1536679]

Voids and compositional inhomogeneities in Cu(In,Ga)Se2 thin films: evolution during growth and impact on solar cell performance

Di Napoli, Simone;Carrisi, Martina;Sozzi, Giovanna;Menozzi, Roberto;
2018

Abstract

Structural defects such as voids and compositional inhomogeneities may affect the performance of Cu(In,Ga)Se2 (CIGS) solar cells. We analyzed the morphology and elemental distributions in co-evaporated CIGS thin films at the different stages of the CIGS growth by energy-dispersive x-ray spectroscopy in a transmission electron microscope. Accumulation of Cu-Se phases was found at crevices and at grain boundaries after the Cu-rich intermediate stage of the CIGS deposition sequence. It was found, that voids are caused by Cu out-diffusion from crevices and GBs during the final deposition stage. The Cu inhomogeneities lead to non-uniform diffusivities of In and Ga, resulting in lateral inhomogeneities of the In and Ga distribution. Two and three-dimensional simulations were used to investigate the impact of the inhomogeneities and voids on the solar cell performance. A significant impact of voids was found, indicating that the unpassivated voids reduce the open-circuit voltage and fill factor due to the introduction of free surfaces with high recombination velocities close to the CIGS/CdS junction. We thus suggest that voids, and possibly inhomogeneities, limit the efficiency of solar cells based on three-stage co-evaporated CIGS thin films. Passivation of the voids’ internal surface may reduce their detrimental effects.
Voids and compositional inhomogeneities in Cu(In,Ga)Se2 thin films: evolution during growth and impact on solar cell performance / Avancini, Enrico; Keller, Debora; Carron, Romain; Arroyo-Rojas Dasilva, Yadira; Erni, Rolf; Priebe, Agnieszka; Di Napoli, Simone; Carrisi, Martina; Sozzi, Giovanna; Menozzi, Roberto; Fu, Fan; Buecheler, Stephan; Tiwari, Ayodhya N.. - In: SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS. - ISSN 1468-6996. - 19:1(2018), pp. 871-882. [10.1080/14686996.2018.1536679]
File in questo prodotto:
File Dimensione Formato  
2018_STAM_Avancini_Voids and compositional inhomogeneities .pdf

accesso aperto

Descrizione: Articolo principale
Tipologia: Versione (PDF) editoriale
Licenza: Creative commons
Dimensione 2.09 MB
Formato Adobe PDF
2.09 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/2853706
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 16
  • ???jsp.display-item.citation.isi??? 16
social impact