Dye-Sensitized and Organic Solar Cells

Dye-sensitized and organic solar cells are expected as low cost solar cells. However, current efficien­cies obtained with small area dye-sensitized and organic solar cells are 11.5% and 8.3%, respec­tively and it must be necessary for those cells to realize more 15% in order to commercialize those cells in widespread applications. Therefore, further development of science and technologies in dye-sensitized and organic solar cells is very important for the end.

Trends in Conversion Efficiency Improvements and Cost Reduction of Solar Cells

Increasing conversion efficiencies of solar cells has huge positive impacts throughout the entire value chain and means less materials, less glass and other module materials, and less installation

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Table 3. Efficiency table of crystalline Si, thin film Si, CIGS, CdTe, dye-sensitized, and organic solar cells reported in “progress in photovoltaics”

Classification

Effic.

(%)

Area

(cm2)

Voc

(V)

Jsc

(mA/cm2)

FF

(%)

Test Centre (date)

Description

Si (single crystal)

25.0±0.5

4.00(da)

0.706

42.7

82.8

Sandia(3/99)

UNSW

Si (multicrystal)

20.4±0.5

1.002(ap)

0.664

38.0

80.9

NREL(5/04)

FhG-ISE

a-Si

9.6±0.3

1.070(ap)

0.859

17.6

63.0

NREL(4/03)

U. Neuchatel

a-Si/nc-Si

/nc-Si(tandem)

12.5±0.7

0.27(da)

2.011

9.11

68.4

NREL(3/09)

United Solar stabilized

a-Si/mc-Si

(tandem)

11.9±0.8

1.227

1.346

12.92

68.5

NREL(8/10)

Oerlikon

a-Si/mc-Si

(tandem)

11.7±0.4

14.23(ap)

5.462

2.99

71.3

AIST(9/04)

Kaneka

CIGS

20.3±0.6

0.5015(ap)

0.740

35.4

77.5

FhG-ISE(6/10)

ZSW

CdTe

16.7±0.5

1.032(ap)

0.845

26.1

75.5

NREL(9/01)

NREL

GaAs

27.6±0.8

0.9989(ap)

1.107

29.6

84.1

NREL(11/10)

Alta Devices

InP

22.1±0.7

4.02(t)

0.878

29.5

85.4

NREL(4/90)

Spire

GaInP/GaInAs /Ge 3-J

(concentration)

41.6±2.5

364-suns

0.3174(da)

3.192

1.696A

88.74

NREL(8/09)

Spectrolab

InGaP/GaAs /InGaAs 3-J (1-sun)

35.8±1.5

0.880(ap)

3.012

13.9

86.3

AIST(9/09)

Sharp

Dye-sensitized

11.2±0.3

0.219(ap)

0.736

21

72.2

AIST(3/06)

Sharp

Organic polymer

8.3±0.3

1.031(ap)

0.816

14.46

70.2

NREL(11/10)

Konarka

(da)=designated illumination area, (ap)=aperture area, (t)=total area.

0 1 1 10 100 1000 10000 100000

Area of cells and modules (cm2)

Figure 4. Chronological improvements in best research-cell efficiencies

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cost. Although many R&Ds for various types of solar cells have been carried out and improve­ments in their conversion efficiencies have been achieved, conversion efficiencies of almost all the solar cells are expected to have limitations. Figure 5 shows future efficiency predictions of various solar cells (original idea by Professor A. Goetz – berger [Goetzberger, Luther, & Willeke, 2001] and modified by M. Yamaguchi [Yamaguchi, 2004]).According to efficiency predictions shown in Figure 5, limiting efficiencies are predicted to be 28.9%, 23.5%, 23.5%, 17.5%, and 16% for crystalline Si, thin-film Si, CIGS as well as CdTe, dye-sensitized and organic solar cells, respectively. On the other hands, because 41.6% efficiency has been realized with concentrator InGaP/InGaAs/ Ge 3-junction solar cells, concentrator 4-junc­tion or 5-junction solar cells have great potential for realizing super high-efficiency of over 50%. In addition, developing new types of solar cells based on new materials and new concepts is also very important to overcome conversion efficiency limitations.

Cost reduction of solar cell modules is also very important for large-scale penetration of PV as a primary energy source. Figure 6 shows com­parison of the projected module price with an extension of the historical experience curve (Swanson, 2006). According to the historical experience curve, a price of $1.40/W will be obtained in 2012. A module price of $1.40/W, coupled with a system price of twice ($2.80/W) should result in a cost-effective grid-connected market in many locations. That means that crys­talline Si is expected to be still the dominant technology in 10 years. As low cost mass produc­tion technologies of CdTe solar cell modules with cost of $0.87/W has already been developed, there must well be several thin-film technologies that are rapidly gaining market share. In addition, concentrator PV is also expected to contribute to large-scale power generation systems. Dye-sen­sitized, organic, and new types of solar cells may also have great potential for their further lowering cost.

Updated: August 2, 2015 — 6:04 am