Morphology Control And Performance Research Of Flexible Printing Large-Area Perovskite Solar Cells

Attribute to the distinguished photoelectric properties of organic-inorganic hybrid perovskite materials,the power conversion efficiency(PCE)of perovskite solar cells(PVSCs)develop rapidly in recent decade,obtaining a breakthrough from3.8%to 25.5%.Meanwhile,due to the intrinsic characteristics of light weight,flexibility and solution processing method,PVSCs also demonstrate the application potential in flexible devices.Although the PCE of flexible PVSCs in laboratory has reached 20%,there are still three challenges in the transformation of large-scale printing production.First,the film forming properties of perovskite precursors on flexible substrate are significantly different from those on rigid substrate,leading to negative crystallization quality after thermal annealing.Next,the spin-coating technology,which is the conventional fabrication method for high-efficiency PSCs at present,is still difficult to achieve the large-area homogeneous polycrystalline films.Finally,the environmental problems caused by lead leakage from degraded PVSCs should not be ignored.In this paper,we explore the current research status of flexible PVSCs,such as poor printability,difficult precise regulation of nucleation and crystallization and insufficient mechanical properties of wearable devices.Focusing on the printing fluid mechanics,preparation of perovskite photosensitive layer,interface regulation and additive modification,we optimize the optical,electrical and mechanical performance of flexible PVSCs through the bionic structure design and crystallization kinetices exploration,and realize the printing fabrication of wearable perovskite solar cells.The main research contents are as follow:1.We calculate the shear impulse transfer relationship between slot-die printing and spin-coating process by regulating the morphology evolution for the active layer of organic solar cells to determine the shear impulse quantitative conversion factor.The morphology and phase separation structure evolution,molecular chain stacking and coarse graining simulation are performed to deeply verify the effectiveness of impulse calculation.By this way,the flexible modules show a champion PCE of8.90%with positive mechanical stability based on 15 cm~2 substrate.This strategy pioneer the application of shear impulse calculation in organic printed electronics.2.The composite transparent electrodes(CTEs)with a combination of PEDOT:PSS and silver mesh/PET are fabricated by slot-die printing and the cost of CTEs can be reduced to 15-20 dollar per square meter.Meanwhile,the CTEs has certain advantages in haze,extinction coefficient and refractive index,and the resistance can be reduced to 4.5-5.0Ω/sq.3.Inspired by spinal crystallization process and flexible structure,a conductive viscous polymer is introduced between the transparent electrode and perovskite layer,which realizes the directional crystal growth through precise control of nucleation site and crystallization rate and bonds the device structure to optimize the critical crack yield strength.Based on this strategy,the PCEs of flexible devices with effective area of 1.01 cm~2 and 31.20 cm~2 reach 19.87%and 17.55%,and the devices can still maintain 85%of initial efficiency after 7000 bending cycles.Meanwhile,we assemble the module into a wearable power supply,which has been applied in flexible electronic products.4.A self-healing polyurethane containing dynamic oxime bond is added to the perovskite film as a scaffold to enhance the perovskite crystallinity and passivate the grain boundaries.Due to the self-healing capability of polymer scaffold,the flexible devices can release mechanical stress and repair grain boundaries at multipole levels,which will recover 88%of the initial efficiency after 1000 cycles at a 20%tensile range.This stretchable device design provides a novel idea for the research of flexible PVSCs.