Recent progress in micromorph solar cells

Abstract

bstractRecently, we have demonstrated that intrinsic hydrogenated microcrystalline silicon, as deposited by the very high frequency glow-discharge technique, can be used as the active layers of p-i-n solar cells. Our microcrystalline silicon Ž represents a new form of thin film crystalline silicon that can be deposited in contrast to any other approach found in . literature at substrate temperatures as low as 2008C. The combination of amorphous and microcrystalline material leads to a 'real' silicon-based tandem structure, which we label 'micromorph' cell. Meanwhile, stabilised efficiencies of 10.7% have been confirmed. In this paper, we present an improved micromorph tandem cell with 12% stabilised efficiency measured under outdoor conditions. Dark conductivity and combined SIMS measurements performed on intrinsic microcrystalline silicon layers reveal a post-oxidation of the film surface. However, a perfect chemical stability of entire microcrystalline cells as well as micromorph cells is presented. Variations of the pri interface treatment show that an increase of the open circuit voltages from 450 mV up to 568 mV are achievable for microcrystalline cells, but such devices have reduced fill factors.

Relationship between Raman crystallinity and open-circuit voltage in microcrystalline silicon solar cells

“…4 and 5) it becomes clear that the interface regions have a major influence on the value of V oc ; and that it is the average crystallinity (factor) of the two interface regions that counts: the more amorphouslike these two interface regions are, on an average, the higher V oc becomes. As the bulk of the i-layer also changes in crystallinity if SC is changed, we are, however, not yet able to say whether it is solely the interface region, as other experiments have suggested [23], or also the bulk material, as proposed in Ref. [24], that determine V oc : To be able to discriminate here between these two hypothesis, further experiments would be necessary.…”

Exploring dark current voltage characteristics of micromorph silicon tandem cells with computer simulations

“…1 In particular the concept of the micromorph tandem solar cell that combines amorphous hydrogenated silicon ͑a-Si: H͒ with microcrystalline silicon ͑ c-Si͒ has become a promising strategy due to its simplicity in the design and to its good performance. 2 The micromorph cell does not incorporate any silicon alloys in the absorber layers; it has the optimal bandgap combination for terrestrial applications, and it is quite stable to light induced degradation. 3,4 Tandem solar cells are regularly characterized by their light current-voltage ͑J-V͒ characteristics under AM1.5 illumination and by the spectral responses ͑SRs͒ under blue bias light and under red bias light.…”

“…3,4 Tandem solar cells are regularly characterized by their light current-voltage ͑J-V͒ characteristics under AM1.5 illumination and by the spectral responses ͑SRs͒ under blue bias light and under red bias light. [2][3][4] To our knowledge the dark J-V curves that have been widely used and studied in single solar cells have not been yet systematically explored in tandem solar cell structures to see if they can provide some useful information about the electrical quality of the device constituents.…”

Growth, structure, and transport properties of thin (>10 nm) n-type microcrystalline silicon prepared on silicon oxide and its application to single-electron transistor

“…[1][2][3][4][5][6] Plasma-enhanced chemical vapor deposition ͑PECVD͒ is not only a common and simple technique employed in the fabrication of these silicon-based devices, it also provides the ability to control the film microstructure such as the grain size and the grain boundary structure. This feature makes it suitable for the development of materials for novel quantum effect devices such as single-electron transistors ͑SETs͒.…”