Laser applications in thin-film photovoltaics

Abstract

We review laser applications in thin-film photovoltaics (thin-film Si, CdTe, and Cu(In,Ga)Se 2 solar cells). Lasers are applied in this growing field to manufacture modules, to monitor Si deposition processes, and to characterize opto-electrical properties of thin films. Unlike traditional panels based on crystalline silicon wafers, the individual cells of a thin-film photovoltaic module can be serially interconnected by laser scribing during fabrication. Laser scribing applications are described in detail, while other laserbased fabrication processes, such as laser-induced crystallization and pulsed laser deposition, are briefly reviewed. Lasers are also integrated into various diagnostic tools to analyze the composition of chemical vapors during deposition of Si thin films. Silane (SiH 4 ), silane radicals (SiH 3 , SiH 2 , SiH, Si), and Si nanoparticles have all been monitored inside chemical vapor deposition systems. Finally, we review various thin-film characterization methods, in which lasers are implemented.

Trigonal‐Bipyramidal and Square‐Pyramidal ChromiumManganese Chalcogenide Clusters, [E2CrMn2(CO)n]2− (E=S, Se, Te; n=9, 10): Synthesis, Electrochemistry, UV/Vis Absorption, and Computational Studies

“…However, implementing the monolithic series connection of flexible thin film PV modules by laser or mechanical scribing, faces various challenges. Careful thermal management with consequences for the complete solar cell structure is needed to avoid warping and partial melting of substrate or contact layers 4. An alternative monolithic in‐situ series connection (ISSC) method was introduced by Merz et al in 2007 5 for hydrogenated amorphous silicon (a‐Si:H) solar modules.…”

Novel series connection concept for thin film solar modules

“…To avoid shunting of individual cell stripes, both first and second contacts of neighbouring cell stripes have to be mutually separated. The required patterning of the different layers, usually denoted as P1 for the groove in the first contact layer, P2 for the groove in the absorber, and P3 for the groove in the absorber and the second contact layer, is typically performed by laser ablation processes with groove widths down to 20 µm . However, also other techniques like lift‐off or mechanical scratching are in use that usually lead to larger groove widths compared with the laser ablation.…”

Optimized grid design for thin film solar panels

“…Moreover, apart from the larger area of solar panels compared to small cells, the subcells are interconnected and the current drains are typically at the sides of each solar panel. Therefore, the generated current needs to travel through both the front and the back contact over much longer distances than in record cells, which represents a major loss factor (Westin et al, 2011;Bartlome et al, 2010).…”