The use of femtosecond UV laser for selective layer processing of CIGS thin-film solar cells

Description

Thin-film photovoltaics (PV) hold great potential for low-cost, high-performance, and flexible solar panel production, even though the PV market is dominated by crystalline silicon technologies. Cu(In,Ga)Se2 (CIGS) based thin-film solar cells are one of the most promising technologies, where recently conversion efficiencies reaching up to 23.6% have been demonstrated on rigid glass substrates [1]. The high efficiency of CIGS thin-film solar cells can be maintained in a full PV panel by subdividing area into small segments that are interconnected in series. This way the photocurrent is limited, reducing resistive losses in thin layers. The series connections consist of three scribing processes called P1, P2, and P3 where the number stands for the coating process step after which they are applied [2] (Figure 1 shows cross-section of a typical CIGS stack and scribing processes P1, P2, P3 type I, and P3 type II).

Here, we will present our findings on high-precision CIGS solar cell processing P1, P2, and P3 using femtosecond (<100 fs) supercontinuum pulsed laser with a tunable UV wavelength. Femtosecond pulses enable highly localized heating due to a time scale shorter than the electron–phonon equilibrium time. This may offer a low heat-affected zone and prevent undesirable melting of CIGS, which causes phase transition and creates conductive channels [3], which cause shortcuts and reduce overall PV module performance. By using femtosecond laser operating at UV wavelength above the bandgap of Al:ZnO we can enable highly controlled P3 scribing due to strong absorption in all the layers. The dependence of ablation depth on laser fluence and overlap ratio will be experimentally studied, with discussions on the corresponding ablation mechanisms.

Period	29 Sept 2024 → 4 Oct 2024
Event title	17th International Conference on Laser Ablation: COLA 2024
Event type	Conference
Location	Heraklion, GreeceShow on map