Rosalinda Inguantaa*, Emanuele Scadutoa, Patrizia Livrerib, Salvatore Piazzaa, Carmelo Sunseria

Transcription

1 Nanostructured materials for solar cells: electrochemical fabrication and characterization Rosalinda Inguantaa*, Emanuele Scadutoa, Patrizia Livrerib, Salvatore Piazzaa, Carmelo Sunseria adipartimento di Ingegneria Chimica, Gestionale, Informatica, Meccanica, Università di Palermo, 90128, Italy bdipartimento di Ingegneria Elettrica, Elettronica e Telecomunicazioni, Università di Palermo, 90128, Italy

2 Goals of the research Electrochemical fabrication of thin film solar cells and nanostructured thin film solar cells, with high efficiency, low fabrication cost and Cd-free ABSORBER: CuInGaSe/S, CuZnSnS BUFFER: ZnS, InS/O, GaS/O, InGaS/O TRASPARENT CONDUCTIVE OXIDE: ZnO, SnO 2 In this work, we present some preliminary results concerning the fabrication of CIS, CIGS thin films and nanowires and ZnS thin films, for p-n junction fabrication. Thin films were deposited on a flexible substrate (PET/ITO) while nanostructures were grown inside the channels of an anodic alumina membrane acting as template.

3 Energy contest

4 Photovoltaic Technologies CuInGaSe % May 24, 2011 An efficiency record of 18.7 percent for CIGS solar cells on plastics has been reported by Swiss researchers at Empa s Laboratory for Thin Film and Photovoltaics.

5 CIGSe 2 Solar Cells National Renewable Energy Laboratory Laboratory scale device 0.42 cm 2 Three stage coevaporation + selenitation High cost Difficult to scale-up Buffer CdS Photon International Magazine, October

6 Aim Electrochemical fabrication of different semiconducting materials 1) Fabrication process cheap and easy to scale-up (room temperature, 10-4 M, low deposition time, Easy to carry out and control, Very high deposition area, Different substrate, Omo- and etero-junctions, Tandem junctions, Tunable stoichiometry and band-gap) 2) Environment-friendly process: Aqueous solvent and Buffer Cd-free ) Nanostructured Thin film nanotechnology can considerably help human capability to reduce the impact of energy production, storage and use. Even if we are still far away from a truly sustainable energy system, scientific community is looking at a further development of energy nanotechnologies by 21 st century. E. Serrano et al. Renewable and Sustainable Energy Reviews, 2009

7 Anodic alumina membrane Ideal honeycomb structure Chemical stability Mechanically resistant Easy to obtain Tailor made morphology Easy to dissolve R. Inguanta et al., App. Surf. Sci., 2007.

8 Schema Fabbricazione nanostrutture metalliche tramite la reazione di cementazione Materiale: Pd 2 Metodo: Cementazione Applicazione: Sensore Materiale: RuO 2 Metodo: Elettrodeposizione Applicazione: Supercapacitori Materiale: CIGS Metodo: Elettrodeposizione Applicazione: Celle Solari Materiale: Cu Metodo: Elettrodeposizione Applicazione: Device elettronici Materiale: Pb Metodo: Elettrodeposizione Applicazione: Batterie Pb-Acido Materiale: LiFePO 4 Metodo: Elettrodeposizione Applicazione: Batterie Li-ione ione Materiale: Pb(OH) /PbO 3 2 Metodo: Cementazione Applicazione: Elettrocatalizzatore Materiale: Zn(OH) 2 /ZnO Metodo: Cementazione Applicazione: Celle Solari Materiale: PbO 2 Metodo: Elettrodeposizione Applicazione: Batterie al Pb-Acido Materiale: Co(OH) 2 /CoO Metodo: Cementazione Applicazione: Catalizzatore Materiale: Ni(OH) 2 /NiO Metodo: Cementazione Applicazione: Catalizzatore Materiale: La(OH) /La O Metodo: Cementazione Applicazione: Catalizzatore Materiale: Ce(OH) /CeO 3 2 Metodo: Cementazione Applicazione: Catalizzatore Materiale: Sm(OH) /Sm O Metodo: Cementazione Applicazione: Catalizzatore Materiale: Er(OH) /Er O Metodo: Cementazione Applicazione: Catalizzatore

9 Nanostructured Solar Cells A. Nadarajah et al., Phys. Stat. Sol. B, 2008 Different configuration High efficiency P. V. Kamat J. Phys. Chem. C 2008 Very high superficial area Tunable band-gap Less probability of carrier recombination

10 Electrodeposition parameters ZnS Electrodeposition 1 h V(SCE) Room Temperature ITO/PET N 2 atmosfere 3 cm 2 Bath Composition Bath1 0.1 M ZnCl 2, 0.2M Na 2 S 2 O 3 CIS/CIGS Electrodeposition V(SCE) ITO/PET and AAM CuSO 4, In 2 (SO 4 ) 3, Ga 2 (SO 4 ) 3, H 2 SeO 3 Bath2 0.1M ZnCl 2, 0.2M Na 2 S 2 O 3 Bath3a 0.3 M EDTA, 0.3 M (CH 3 COO) 2 Zn, 0.01/0.3M Na 2 S 2 O 3 Bath3b 0.1/0.2 M EDTA, 0.1/0.2 M (CH 3 COO) 2 Zn, 0.1/0.2 M Na 2 S 2 O 3 Bath3c 0.2 M EDTA, 0.2 M (CH 3 COO) 2 Zn, 0.1 M Na 2 S 2 O 3 Bath M ZnSO 4, M Na 2 S 2 O 3

11 CIS Nanowires Cu In 2SeO3 12H 13e CuInSe 2 6H2O Cu 0.16 In 0.18 Se 0.66

12 CIGS Nanowires Cu In Ga 2SeO3 12H 16e CuInGaSe 2 6H2O R. Inguanta et al., Electr. Solid State Lett., 2010.

13 CIGS Nanowires Chatodic photo-current Optical Band-gap ~1.56 ev

14 CIGS Thin Films CIGS su ITO/PET p-type Eg= 1.5 ev

15 ZnS Thin Films ZnS su ITO/PET S 2 Zn O H S 2e 4e ZnS 2S 3H 2 O

16 ZnS Thin Films Zn/(Zn+S) / % at ,001 0,002 0,003 0,004 0,005 0,006 0,007 0,008 0,009 Na 2 (SO 2 ) 3 Concentration/ M

17 ZnS Thin Films Anodic photo-current V V 0.2V / SCE ZnS 2e 0.2V / SCE Zn H 2 Zn S O 2h 2 ZnO 2H

18 ZnS Thin Films Optical Band-gap ev The elaboration of the photocurrent spectrum led to a optical gap of about 3.43 ev that is less than crystalline ZnS (3.76 ev). This difference must be due to differences in the shortrange order between our film (that is amorphous) and crystalline film. Different short-range order implies the formation of defective structures with high density of localized states within the mobility gap.

19 Conclusions: CIGS CIS and CIGS TFs and NWs were fabricated on ITO/PET and into AAM, respectively, by one-step deposition at different applied potentials and room temperature. XRD analysis showed an amorphous nature. SEM analysis showed that TFs were comprised of clusters of smaller particles while perfectly cylindrical wires were obtained in AAM. Photoelectrochemical measurements showed cathodic photocurrent and optical gaps of 0.97 and 1.56 ev for CIS and CIGS NWs, respectively.

20 Conclusions: ZnS Thin films of ZnS were fabricated on ITO/PET by onestep potentiostatic deposition from different electrolytes at room temperature. Tunable composition was achieved by adjusting electrolyte composition. SEM analysis showed that thin films consisted of nm nanoparticles with a thickness of nm. Photoelectrochemical measurements showed anodic photocurrent and optical gap of about 3.40 ev and also revealed the presence of a defective structure with an high density of localized states in the mobility gap.

21 Thanks for your attention

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23 Template Electrosynthesis a b I c f d II III IV e -

24 CIGS Nanowires

25 Electrochemical deposition Cheap (room temperature, 10-4 M, low deposition time) Easy to carry out Easy to control Very high deposition area Flexible substrate (ITO on PET or Glass, AAM, etc) Easy for nanostructure fabrication Absober (CIGS) Buffer (ZnS) Omo- and eterojunctions Tandem junctions Optimum stoichiometry Tunable band-gap

26 CIGSe 2 Solar Cells Nanosolar 20 nm 16.4% 11.3%