Femtosecond Laser Processing Of Functional Layers Of Perovskite Solar Cells And Their Applications

Nowadays,the certified efficiency of single-junction perovskite solar cells is as high as 25.7%,which is comparable to photovoltaic cells based on traditional inorganic semiconductors such as silicon.In order to achieve large-area power generation and high-voltage networking,scalable preparation has become a key technical issue.In the process of solving this problem,it is not only necessary to explore uniform,efficient,and inexpensive high-throughput preparation methods to reduce the non-uniform loss between layers,but also to improve the utilization of inactive areas to reduce material waste.Compared with traditional mechanical scribing and mask etching,laser scribing is considered to be the key to improving the effective area.Among them,the ultrafast laser has the characteristics of non-thermal processing and precision ablation,which can minimize the damage to the devices and become an ideal tool.However,for the novel perovskite solar cells,which contain five functional layer materials with widely different properties,there is no excellent laser processing solution.Moreover,some studies only focus on the laser processing technology,and do not deeply study the femtosecond laser ablation process of functional layer material.On this basis,this thesis systematically studies the femtosecond laser ablation mechanism of the FTO layer,perovskite layer,Spiro-OMeTAD layer and Au layer of perovskite solar cells,and calculates the ablation thresholds of functional layer.At the same time,the processing technology and influencing factors of the series interconnect structure(P1,P2,P3)in the perovskite solar cell module are studied.For multilayer thin-film composite devices,a separate scribing method was proposed to achieve cleaner removal.Furthermore,high geometric fill factor(GFF)perovskite solar cells,high-performance semitransparent perovskite solar cells,and series-integrated ultra-high voltage perovskite solar cells were fabricated.The research results obtained are as follows:1.The effects of pulse duration,exposure time and scanning mode on femtosecond laser processing were studied.With the decrease of the laser pulse width,the heat-affected area of the ablated hole gradually decreases,and the processing effect is better.Long-pulse exposure enables cleaner drilling compared to short-pulse exposures.Relative to frequency triggering,position-based triggering of pulses shows higher accuracy and uniformity.And the degradation process of perovskite under femtosecond laser irradiation was studied.The organic part in the perovskite volatilizes first,and the lead iodide remaining at the edge of the ablation hole can form a type I heterojunction with the perovskite.Furthermore,the processing parameters and ablation thresholds of femtosecond laser for perovskite,FTO,Spiro-OMeTAD and Au were optimized.2.The femtosecond laser processing and removal process of the series interconnect structures(P1,P2 and P3)were studied.For composite materials consisting of multiple films,a separate scribing method can be used,that is,precise control of energy deposition to remove materials with large differences in physical properties.The widths of the P1,P2 and P3 scribe lines were optimized,and a perovskite solar cell module with a photon-to-electron conversion efficiency(PCE)of18.88%and a GFF of 97%was designed and fabricated.5×5 cm~2ultra-high voltage perovskite solar cells with series integration numbers of 4,9,25 and 100 were designed and fabricated.Among them,the unpackaged 5×5 cm~2ultra-high voltage perovskite solar cell with a series integration number of 100 has a maximum voltage output of 103.5 V,and maintains a storage stability of 500 h.3.Based on the optimized laser processing parameters and the non-thermal processing properties and spatial confinement effect of femtosecond lasers,a fabrication strategy for semi-transparent perovskite solar cells is proposed.A single-junction semi-transparent perovskite solar cell with a PCE of 17.5%and an average visible transparency(AVT)of 18.2%and a 5×5 cm~2semi-transparent perovskite solar cell module with a PCE of 9.1%and an AVT of 37.7%were prepared.Moreover,rationally designed patterns can also be directly imprinted on perovskite solar cells while maintaining a PCE of 14.4%.In addition,this strategy was further extended to commercial amorphous silicon solar cells,which also showed excellent performance.