CNT-ONLY CELLS (FIGURE 1A)

The photocurrent decreases linearly with increasing cell potential applied to the load V (figure 3 a). We extract the open-circuit voltage VOC by ex­trapolating the I-V characteristic to I = 0 and the short-circuit current ISC

image014

Подпись: Carbon Nanotube Solar CellsFIGURE 2: Layout of DSSCs and equivalent circuits. Both basic DSSCs (a) and tested optimization strategies are (b-d) are depicted. The circuit diagram is modeled after [41]. The alternative construction techniques lead to changes in the cell’s electrical model, which are highlighted.

by extrapolating to V = 0 (table 1). Both ISC and VOC of the enriched mix­ture cells increase with decreasing CNT coverage of the semiconducting active electrode. Similarly, the high-density cell of the regular mixture of nanotubes has a lower ISC and VOC than the low-density cell. The power transfer curves (figure 3b) show a peak power transfer of Pmax that occurs when the impedance of the load reaches R. The low-density enriched as well as the low-density regular cells deliver more power to the load than their high-density counterparts. This is consistent with both ISC and VOC being larger.

TABLE 1: Parameters of CNSCs.

Cell Type

Ra

VOC

Isc

Pmax

Rmac

ns

nm

kQ/a

mV

nA

nW

MQ

a. u.

a. u.

Enriched High Density

3.4

43.6

47.0

0.57

0.71

521

58

(black)

Enriched Low Density

62.7

208.5

243.4

11.50

0.82

121

13

(blue)

Regular High Density

30.2

9.3

4.4

0.01

5.55

36

18

(ma­

genta)

Regular Low Density

50.3

21.4

19.0

0.17

2.45

29

15

(green)

Enriched Medium Density

46.1

154.1

91.2

5.32

3.01

136

15