Scientists from China's Jinan University, CoreTech Integrated Limited and Chinese Academy of Sciences have used selective nanosecond-pulse, laser-induced ablation to create a perovskite solar module with a reduced heat-affected zone.
The team showed that a nanosecond pulse laser can deliver a reduced heat-affected zone due to the small thermal diffusion coefficient (Dt) of the perovskite material, contributing to the accomplishment of a high geometric filling factor (GFF) of up to 95.5%. In addition, the monolithic interconnection quality was improved by finely lifting off the capping layers on indium tin oxide and identifying the residue within the scribed area. As a result, a certified aperture area efficiency of 21.07% under standard 100 mW cm−2 AM1.5G illumination was achieved with a high photovoltaic fill factor exceeding 80%.
The researchers built the cells with a transparent conductive oxide (TCO) substrate, a hole transport layer (HTL) the perovskite layer, an electron transport layer (ETL), and a silver (Ag) metal contact. They interconnected the solar cells via P1, P2, and P3 scribes.
“We used a 30 ns laser with a wavelength of 1064 nm to scribe P1 because a wide band gap indium tin oxide (ITO) has free carrier absorption in the near-infrared region,” the scientists said noting that the high pulse-to-pulse overlap is used in P1 patterning to obtain clean and smooth scribe line valleys. “In the P2 patterning step, the perovskite layer, as well as other functional layers are removed to construct interconnections between the sub-cells. In the P3 step, the top electrode is removed along with all other layers except the ITO, to exclude shunting of adjacent sub-cells of the device.”
The scientists described the manufacturing process based on the nanosecond laser as “good enough” to obtain the high-quality interconnection for perovskite solar modules.
“The champion perovskite solar module yielded a certified aperture efficiency of 21.07% and a geometric fill factor of 95.5%, which is one of the highest reported so far,” they concluded. “This result leads the way to further simplification and reliability in perovskite solar module production.”
