Tecnología para la fabricación de celdas solares de alta eficiencia basadas en películas delgadas de CdS/CdTe

(1)

1 1

Centro de Investigación y de Estudios

Avanzados del IPN

Departamento de Física Aplicada

Grupo de Celdas Solares

Juan Luis Peña

(

jlpena@mda.cinvestav.mx)

Tecnología para la fabricación de celdas

solares de alta eficiencia basadas en

(2)

2

Proyecto apoyado por Fordecyt-Conacyt

“Creación del laboratorio de energías

renovables del sureste (LENERSE)”

Subproyecto Energía Solar

Coordinador:

Dr. Juan Luis Peña

CINVESTAV-IPN

(3)

3 3

Outline

• Introduction

• Our CdS/CdTe solar cells

• Experimental results

(4)

4

Celdas fabricadas en el 2005

(5)

(6)

(7)

(8)

8 VIDRIO ITOZnO CdS CdTe Intermixing

(9)

9

Our CdS/CdTe solar cell

process (2011)

• ITO comercial

• Our ITO (2012)

• ZnO (100-120 nm) by sputtering

• CdS (130-160 nm) by sputtering without intentional

treatment

• CdTe (8-10 μm) by CSS, gas mixed Ar/O2

• Activation: CHClF

₂

+ Ar

• Cu/Mo (5 nm / 750 nm) by sputtering.

• Soaking: depending on EQE spectra

(10)

10

Optimizing the growth parameters of ITO for

application in solar cells CdS/CdTe

𝐽𝑖𝑚𝑚𝑦 𝐿. 𝐵𝑢𝑒𝑛𝑓𝑖𝑙1 , 𝐼𝑛é𝑠 𝑀. 𝑅𝑖𝑒𝑐ℎ1 , 𝐽𝑢𝑎𝑛 𝑀. 𝐶𝑎𝑚𝑎𝑐ℎ𝑜2 , 𝑉í𝑐𝑡𝑜𝑟 𝑅𝑒𝑗ó𝑛2 , 𝐽𝑢𝑎𝑛 𝐿. 𝑃𝑒ñ𝑎2

1Facultad de Ingeniería, Universidad Autónoma de Yucatán, Av. Industrial no contaminantes por anillo periférico norte s/n Apdo. Postal 150 Cordemex, Mérida, Yucatán, México. 2Departamento de Física Aplicada, CINVESTAV – IPN Mérida, C.P 97310 Mérida, Yucatán, México.

V International Conference on Surfaces, Materials and Vacuum September 24-28, 2012 Tuxtla Gutierrez, Chiapas

• Our optimized ITO thin film was deposited by using the following conditions:

Ts=550 °C, RF-power=100 W, Pressure of Ar= 15 mTorr, Time of growth= 7 min.

• Our ITO thin film had better electrical, optical and morphological characteristics

(11)

11 11

Clorinacion

Our CdS/CdTe solar cell

process

(12)

(13)

13

(14)

14

(15)

(16)

16

Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C.

V International Conference on Surfaces, Materials and Vacuum September 24-28, 2012 Tuxtla Gutierrez, Chiapas

(17)

17

(18)

(19)

(20)

20

Comparación del uso en el proceso

de activación de la celda solar de

Freon HCF

₂

Cl

vs

(21)

21

Uso de

Freon HCF

₂

Cl

(22)

22

Energy and Climate Outlook: 2012

Global Greenhouse Gas Emissions

Compuestos con cloro y flúor (CFC, HCFC, HFC) Perfluorocarbonos (PFCs) formula C_nF_2n+2

Chlorofluorocarbon was found mostly in refrigerators, aerosol cans and air conditioners. But since the Montreal Protocol the use of CFCs has practically been eliminated. Cooling systems

(23)

23

Actualmente estamos probado gases para

la activación de la celda solar que

contienen cloro y que son mas amigables

con el medio ambiente

(24)

24

Material Source TLV-TWA1

(ppm) STEL2 (ppm) IDLH3 (ppm) ERPG2 4 (ppm) Critical Effects Cadmium compounds CdTe and CdS deposition CdCl2 treatment 0.01 mg/m3 (dust) 0.002 mg/m3 (fumes) - - NA Cancer, kidney

Table 2. Some Hazardous Materials used in Current PV Manufacturing Table 2. Some Hazardous Materials used in Current PV Manufacturing

Table 2. Some Hazardous Materials used in Current PV Manufacturing

(ppm) STEL2 (ppm) IDLH3 (ppm) ERPG2 4 (ppm) Critical Effects Cadmium compounds CdTe and CdS deposition CdCl₂ treatment 0.01 mg/m3 (dust) 0.002 mg/m3 (fumes) - - NA Cancer, kidney

Effects of long-term or repeated exposure

The substance may have effects on the kidneys and lungs. This may result in kidney impairment and tissue lesions. This substance is carcinogenic to humans.

Cadmium dichloride (CdCl

₂

)

OVERVIEW OF POTENTIAL HAZARDS V.M. Fthenakis

ENVIRONMENTAL DATA:

The substance is toxic to aquatic organisms.

Bioaccumulation of this chemical may occur in plants.

(25)

(26)

26

(27)

27

Grain size of CdS/CdTe solar cell

27

• Cu/Mo as a back contact.

• Good grain size and few

holes.

• We can see grains that

coalesced .

(28)

28

Details of the Mo/Cu/CdTe surface

28

● The grain CdTe has roughness.

● The series resistance depend of how the Mo contact is deposited

● Then, the series resistance also depend on CdTe surface.

AFM image

SEM image

(29)

(30)

(31)

(32)

32 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 -30 -25 -20 -15 -10 -5 0 5 10

J(mA/

cm

2

)

V(V)

Oriel simulator, 14.0 %

Sun, 14, 6 %



=14.6%

área=0.21 cm2

(33)

33

Eficiencias obtenidas

en

celdas solares de áreas mayores

(~1 cm

2 )

(34)

34 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 -0.025 -0.020 -0.015 -0.010 -0.005 0.000 0.005 J (A/ cm 2 ) V (V) 5T42 5T43 5T52 Name Area (cm2) I (mA) J (mA/cm2) Voc (V) FF (%) Rs (-cm2) Rsh (-cm2)  (%) 5T42 1.0089 21.3 21.1 0.775 56.7 7.4 278.0 10.6 5T43 0.9658 18.5 19.2 0.772 57.0 9.9 492.0 9.4 5T52 2.71 52.2 19.23 0.745 52.4 10.8 304.0 7.5 34 ● We have good reproducibility in Voc and FF and electrical characteristics for areas of 2.7 and 1cm2

Solar cells: 1 cm

2

vs

2.71 cm

2

(35)

35

Dark J-V of CdS/CdTe solar cells

35

● 5T52 (big area) has a behavior as

an ideal p-n juntion.

● 5T42 and 5T43 of 1cm2 have

shunting due to recombination

current related with grain boundary phenomena.

● However the cells 5T42 and 5T43 are better than 5T52. It means that the shunting effect in darkness does not affect the illuminated solar cell characteristics. This phenomena is investigated. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1E-7 1E-6 1E-5 1E-4 1E-3 0.01 0.1 J (A/ cm 2 ) V (V) 5T42 5T43 5T52 Rsh effect Rs effect

(36)

36



=14.6%

área=0.21 cm2

(37)

37

EQE of CdS/CdTe solar cell

37 ● 1 is for as born solar cell. The CdS

sharpness is observed at 500-520 nm. In this case is observed a strong recombination current for wavelenghts around 825 nm.

● 2 After 20 minutes of light soaking the EQE spectra is changed. We can observe that EQE is improved.

● After other 20 minutes of light soaking, again the EQE spectra is improved and the recombination current is almost eliminated.

● We concluded that in our fabrication process, the light soaking is needed. 400 450 500 550 600 650 700 750 800 850 EQ E (u .a .) (nm) 1 2 3

Typical EQE spectra obtained in our solar cells.

(38)

38 0.0 0.2 0.4 0.6 0.8 -0.02 -0.01 0.00 0.01 0.02 Area 0.22 cm2 10.3 % 11.4 % J(A/ cm 2 ) V(V) one soaking two soakings

SOAKING

(39)

39

Nicola Romeo

y

Alessio Bosio

University of Parma, Italy

Juan Luis Peña Chapa

CINVESTAV-IPN UNIDAD MERIDA

Colaboracion para la fabricacion de paneles y

celdas solares en la Universidad de Parma y en

(40)

40

Prof. Nicola Romeo en

su laboratorio

mostrando el panel

FV no. 9 fabricado

durante la primera

producción de la línea

automática de la

compañía italiana

Arendi en Milan.

(41)

41

Voc= .810 V

Isc = 17.2 mA/cm2



=12.1%

área= 1.02 cm

2 Celda solar fabricada en la

Universidad de Parma

(42)

42 -2 0 2 4 6 8 10 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

Solar panel CdTe 100 cm2 AM 1.5 filter 1.01 sun Room temperature

C

urre

nt

d

en

si

ty

(mA/

cm

2

)

Voltage (V) V oc= 7.4 V Isc=-0.2003 A P_max=-0.848 W FF=57.2%  = 8.71%

-2

0

2

4

6

8

10 -2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0 Solar panel CdTe 100 cm

2 AM 1.5 filter

1.01 sun

Room temperature

C

urre

nt

d

en

si

ty

(mA/

cm

2

)

Voltage (V)

V

oc

= 7.4 V

Isc

=-0.2003 A

P

_max

=-0.848 W

FF=57.2%



= 8.71%

_{10.8 %}

Panel de 100 cm

2

_{fabricado en la Universidad de Parma}

(43)

43

(44)

44

(45)

45 1st_Laser Scribing Washing & drying machine

Sputt. TCO Sputt. CdS _{with CHF}

3 CSS CdTe Ar ambient Treat. Chamber (CHF2Cl) Back contact As2Te3 & Mo (sputt.) 2nd_Laser Scribing 3 rd_Laser Scribing

The industrial process

RT 400°C TCO RT Laser Scribing 250°C CdS 500°C CdTe 400°C - Cl₂ treatment RT Laser Scribing 300°C Back contact RT Laser Scribing

(46)

46

Soda Lime glass

TCO

Soda Lime glass

1st _{laser scribing} 2nd laser scribing

Soda Lime glass

CdS/CdTe

3rd _{laser scribing} Buffer

layer+Mo

The laser scribing

Charge carriers flow

(47)

47

(48)

48

(49)

49

Foto de la linea de deposito del contacto

metalico en Arendi

(50)

50

The better performance in our CdTe/CdS

solar cell is due to:

1. The utilization of ZnO buffer layer.

2. The CdS grown by RF sputtering.

3. The chlorination with CHClF

₂

(chlorodifluoromethane

)

gas mixed with other

gases.

4. The back contact deposited by sputtered

bilayer of Cu/Mo.

(51)

51

Conclusions

• The methodology allows repeatable solar

cells.

• As born solar cell needs light soaking for

improving.

• The technology can be used to fabricate

CdS/CdTe thin film solar cells of high

efficiency

(52)

52

¡GRACIAS¡

¿PREGUNTAS?

Dzibilchaltún

(53)

53