A group of materials scientists from the University of Rome Tor Vergata in Rome, in collaboration with researchers in Germany, have reduced the cell-to-module losses in perovskite solar modules and fabricated a 20*20 cm mini panel with a power conversion efficiency of 11.9%.

The study has been published in the journal Advanced Energy Materials. Scientists from the Institute of Structure of Matter ISM — CNR in Italy, Greatcell Italy, and  Technische Universität Dresden in Germany collaborated with their counterparts in the Roman university.

The scientists used the technique of laser ablation to nullify electrical losses by limiting the flow of current in perovskite solar cells. The laser ablation process is a subtractive method that fabricates micropatterns through the removal (ablation) of a small fraction of a substrate material under a focused pulsed laser beam.

The scientists patterned the solar cell area into solar cell stripes interconnected in series to enhance the size of the thin-film photovoltaic (PV) module. The group claimed that laser technology helps overcome the challenges in the fabrication of metal-halide perovskite modules. High power conversion efficiency can be achieved with smaller solar cells on a laboratory scale that can later be molded to suit industry-relevant sizes.

Separating contact layers to isolate cells

The laser patterning is based on controlled energy input, resulting in clean and regular scribe lines. The scientists investigated the layer structure of planar perovskite solar cells in three patterning steps — P1, P2, and P3. The group determined the width of the perovskite cells to electrically isolate the two from each other by separating the two contact layers with P1 and P3. An absorber layer was achieved by maintaining the P2 structuring between P1 and P3 to provide an electrical interconnection.

To achieve a higher cell-to-module efficiency ratio, the scientists kept the area between P1 and P3 as small as possible to avoid the challenges of preserving the integrity of the edge regions of the absorber layer during P2 patterning. The laser beam possesses a Gaussian intensity distribution, a fundamental distribution technique in science used to model large phenomena in the world.

The scientists implemented the P1, P2, and P3 laser parameters and reduced the electrical losses in larger areas of the thin-film perovskite cells, and achieved a stabilized efficiency of 11.9% and 2.3 W on an active area of 192 cm, which the group claims to be the highest reported efficiency in the literature till now.

Earlier this month, scientists at the University of Toronto used quantum mechanics to achieve a power conversion efficiency of 23.9% in an inverted perovskite solar cell structure.

Mercom reported that materials scientists at the UCLA Samueli School of Engineering introduced a new surface treatment to overcome the long-term deterioration of perovskite solar cells when exposed to sunlight.