Silicon thin film e coating per il fotovoltaico

Size: px
Start display at page:

Download "Silicon thin film e coating per il fotovoltaico"

Transcription

1 Silicon thin film e coating per il fotovoltaico Paola Delli Veneri UTTP-Unità Tecnica Tecnologie, Laboratorio Materiali e Dispositivi di Base M.Luisa Addonizio UTTP-Unità Tecnica Tecnologie, Unità Tecnica Film Ottici Speciali ENEA Portici Research Center

2 Photovoltaic production for different technologies Crystalline silicon based solar cells are the most successful in industrial production. Source: Navigant Consulting 5 years scenario Source: EPIA

3 The advantages of thin film technologies Reduction of the active material 350 Reduction of production energetic costs Series interconnection of cells by laser scribing Spessore in micron Waste taglio wafer Dispositivo

4 Heliantos Products can be made lightweight and flexible

5 Announced Production Capacities by Technology Equally competitive technologies are amorphous/micromorph Silicon, CdTe and Cu(In,Ga)(S,Se)2 thin films. Thin Film Industries: more than 130 companies in the world 68 companies are silicon based The reason is probably that several companies offer turn-key systems. Source: Arnulf Jaeger-Waldau EU JRC IE Ispra SLO-PV 2008, Ljubljana

6 Companies offering production lines: Oerlikon Solar Present best 1.4 m 2 micromorph tandem R&D module Initial power:146 W ( =10.8%) Expected stabilized power: 130 W O. Kluth et al., Presented at the 24 rd EU PVSEC (Hamburg 2009)

7 Companies offering production lines: Applied Materials W. Stein et al., Presented at the 24 rd EU PVSEC (Hamburg 2009) Best 5.7 m 2 single junction a-si module fabricated in the production plant of T-Solar Initial power:430.2 W ( =7.5%) Expected stabilized power: W ( =5.8%) Italian customer of AMAT: Moncada Energy Group (Sicilia) M. Vetter et al., Proceedings of 23 rd EU PVSEC (Valencia 2008)

8 Result on 5.7 m 2 module presented ad 24th EU PVSEC, Hamburg 2009

9 Single junction amorphous silicon p-i-n solar cell Glass E electons Solar light holes TCO p i n Metal contact Sun light enters through the p layer which is called window layer The intrinsic layer is the active material The photocarriers are swept away by the built-in electric field to the n-type and p- type layers. Efficiency record for stabilized single junction a-si:h device: =10.09% i-layer thickness = 250 nm!! S. Benagli et al., Presented at 24 rd EU PVSEC, Hamburg 2009

10 a-si/ c-si micromorph tandem solar cells blue Glass a-si:h c-si:h Solar light ZnO/Ag red TCO p i n p i n Advantages: The light-induced degradation typical of a-si is effectively reduced Better utilization of the solar spectrum m 2-3 m Micromorph tandem Amorphous single junction D. Dominé et al., Presented at the 23 rd EU PVSEC Valencia 2008

11 a-si:h/a-sige:h/nc-si:h triple-junction solar cells blue a-si:h a-sige:h a-sige:h Sun light green red TCO p i n p i n p i n Ag Stainless Steel active-area: 0.25 cm 2 B. Yan, United Solar Ovonic,, IEEE 2008

12 a-si:h/ c-si 1-x Ge x :H double-junction tandem solar cells T. Matsui et al., Proceedings of the 23 rd EU PVSEC (Valencia 2008) =11.2% has been obtained by using μc-si 0.9 Ge 0.1 :H layers, with bottom cell thickness less than 1 μm.

13 Thin film silicon solar cells on plastic substrates The use of transparent plastic substrates, which are often easily damaged by ultraviolet, light requires the substrate (n-i-p) configuration n-i-p micromorph tandem solar cell on plastic substrates EU-project Flexcellence T. Soderstrom et al., Appl. Phys. Lett. 94, 2009.

14 Thin film silicon solar cells on metal substrates Semi-transparent, micro-structured metal substrate configuration Amorphous solar cell with initial efficiency of 5.86%

15 Main research topics on thin film silicon solar cells TCO surface for improved light trapping High deposition rate (>1 nm/s) Tandem cell with initial efficiency of 11.3% at 2nm/s has been realized at Sanyo s R&D

16 Intermediate reflector Using an appropriate material as intermediate reflector in between the two component cells, it is possible to enhance the photocurrent of the top cell without increasing the thickness, thus improving also the device stability. Intermediate reflector for p-i-n tandem solar cells. Silicon oxide (D. Dominé, Phys. Status Solidi 2, ) Silicon nitride (P. Delli Veneri et al., Proc. of the 23 rd EU PVSEC Valencia 2008) Intermediate layer Asymmetric intermediate reflector for n-i-p tandem solar cells back reflector T. Soderstrom et al., Presented at 24rd EU PVSEC, Hamburg 2009

17 ENEA activities on thin film silicon solar cells Development of transparent and conductive oxide (TCO) films Tandem micromorph solar cells Third generation approach

18 Light trapping issues The use of a rough transparent conductive oxide (TCO) layer is essential in order to increase the efficiency of thin film solar cells. Requirements for high-quality TCO: High electrical conductivity High transparency High light-scattering ability

19 ENEA results on TCO development ZnO films deposited by Low Pressure Chemical Vapor Deposition (LP MOCVD) Deposition system a-si:h p-i-n J (ma/cm 2 ) ZnO SnO 2 V(V) ZnO as deposited ZnO after surface treatment

20 ENEA results on micromorph tandem solar cells a-si c-si Deposition system p i n p i n 270 nm 1.5 m 14 Technique: VHF PECVD at 100 MHz Deposition temperature: 150 C Substrate: Glass/SnO 2 Asahi U-type Area: 1 cm X 1 cm J (ma/cm 2 ) iniziale = 11.3 % stabilizzata > 10 % 0 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 V (V)

21 Next generation of micromorph tandem cells Solar spectrum The idea is to engineer new materials with tailored band gap, which absorb photons in a dedicated energy range, by using the quantum confinement effect. Modified micromorph tandem solar cell blue Sun light glass a-si:h c-si:h ZnO/Ag red TCO p i n p i n Si QDs Si QD based top cell E g ~ ev PECVD growth of Si QDs in SiN x

22 Thank you for your attention! Paola Delli Veneri