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A. Shah
(2) Amorphous silicon layers have a much stronger absorption than crystalline
silicon layers (see Chap. 3, Sect. 3.2.2)
Because of (2) it became possible to fabricate amorphous silicon solar cells, which
had to be kept very thin, in order not to suffer unduly from the SWE.
Because of (1) these amorphous cells have a spectral response that is different from
the spectral response of crystalline silicon cells (see Chap. 3, Sect. 3.6), rendering
amorphous cells particularly suitable for use with indoor lighting.
6.1.3 Using Amorphous Silicon Layers in Heterojunction
Solar Cells
Amorphous silicon (a-Si:H) thin films are currently widely used as passivation layers
for crystalline silicon solar cells, leading, thus, to heterojunction cells (HJT cells),
as described in Chap. 7, next-up. HJT cells work with passivated contacts on both
sides. These contacts, consist of an approximately 5 nm thick layer of intrinsic
amorphous silicon (which is directly touching the crystalline silicon wafer), followed
by an appropriately 15 nm thick doped (p-type or n-type) a-Si:H layer. A transparent
conductive oxide (TCO), usually indium tin oxide (ITO) caps the doped layers, to
provide lateral charge transport to the screen-printed Ag fingers. The typical structure
of a HJT cell is shown in Fig. 6.8, for the example of a Bifacial HJT solar cell, as
developed by IMT Neuchâtel for Meyer Burger [10].
The critical interface is between the c-Si wafer and the intrinsic a-Si:H layer.
Figure 6.9 shows a micrograph of this interface, presented by Sara Olibet in her
Ph.D. thesis [11]. As noted there “Best passivation necessitates an abrupt and flat
interface of the a-Si:H layer to c-Si”. One remarks in Fig. 6.9, the crystallographic
abrupt interface, which is indeed essential for passivation properties.
It is to be expected that intensive research will continue in this field, with the goals
of (a) improving further the already excellent passivation properties; (b) studying
the long-term behaviour of these structures—in order to completely avoid any danger of encountering degradation effects; (c) increasing throughputs and simplifying
production steps—in order to reduce the fabrication cost of HJT solar cells.
6.2 Amorphous Silicon Solar Cells
For a recapitulation on this type of solar cells, see also [12].
A. Shah
(2) Amorphous silicon layers have a much stronger absorption than crystalline
silicon layers (see Chap. 3, Sect. 3.2.2)
Because of (2) it became possible to fabricate amorphous silicon solar cells, which
had to be kept very thin, in order not to suffer unduly from the SWE.
Because of (1) these amorphous cells have a spectral response that is different from
the spectral response of crystalline silicon cells (see Chap. 3, Sect. 3.6), rendering
amorphous cells particularly suitable for use with indoor lighting.
6.1.3 Using Amorphous Silicon Layers in Heterojunction
Solar Cells
Amorphous silicon (a-Si:H) thin films are currently widely used as passivation layers
for crystalline silicon solar cells, leading, thus, to heterojunction cells (HJT cells),
as described in Chap. 7, next-up. HJT cells work with passivated contacts on both
sides. These contacts, consist of an approximately 5 nm thick layer of intrinsic
amorphous silicon (which is directly touching the crystalline silicon wafer), followed
by an appropriately 15 nm thick doped (p-type or n-type) a-Si:H layer. A transparent
conductive oxide (TCO), usually indium tin oxide (ITO) caps the doped layers, to
provide lateral charge transport to the screen-printed Ag fingers. The typical structure
of a HJT cell is shown in Fig. 6.8, for the example of a Bifacial HJT solar cell, as
developed by IMT Neuchâtel for Meyer Burger [10].
The critical interface is between the c-Si wafer and the intrinsic a-Si:H layer.
Figure 6.9 shows a micrograph of this interface, presented by Sara Olibet in her
Ph.D. thesis [11]. As noted there “Best passivation necessitates an abrupt and flat
interface of the a-Si:H layer to c-Si”. One remarks in Fig. 6.9, the crystallographic
abrupt interface, which is indeed essential for passivation properties.
It is to be expected that intensive research will continue in this field, with the goals
of (a) improving further the already excellent passivation properties; (b) studying
the long-term behaviour of these structures—in order to completely avoid any danger of encountering degradation effects; (c) increasing throughputs and simplifying
production steps—in order to reduce the fabrication cost of HJT solar cells.
6.2 Amorphous Silicon Solar Cells
For a recapitulation on this type of solar cells, see also [12].