| Perovskite solar cells（PSCs）have experienced substantial growth because of their distinguished property and huge commercial value.Nevertheless,a key bottleneck hindering its commercialization at present is that perovskite（PVSK）degrades over time when exposed to light,heat,water,and oxygen.In addition,the organic functional layer and electrode layer of the component also degrade to different degrees under external pressure sources.In view of the above issues,this thesis investigates the perovskite interface modification,cross-links the perovskite layer and the charge transport layers,and develops stable electrode materials and effective encapsulation methods based on inverted PSCs devices to enhance the stability of PSCs while taking into account the efficiency.The primary task involves:（1）Developing an ultra-thin film of a functional hydrophobic polymer,polychloro-p-dimethyl benzene（Parylene C）,which can largely improve the operational lifetime of PSCs as a surface finish.Chemical vapor deposition（CVD）is adopted to deposit the Parylene C film with adjustable thicknesses on the perovskite surface,which is thin adequately to afford tunnel contact but is also sufficiently shielding to protect the perovskite layer.Besides,it is demonstrated that the Parylene C film can reduce the perovskite surface defects by interacting with the uncoordinated Pb center and act as an effective hole-hindering barrier in the middle of PVSK and PCBM for decreasing carrier recombination.As a result,the PSC using a～4 nm Parylene C layer exhibits a remarkably improvement in open-circuit voltage and fill factor（FF）,resulting in an efficiency boost from 19.4%to 21.7%.Moreover,the Parylene C-based PSCs have attained long-term thermal and operational stabilities with good reproducibility.Without encapsulation,the degradation was limited to 11%after 500h of aging under ambient atmosphere/dark,85°C/N2,or constant illumination/N2 conditions.（2）Developing a dual crosslinking strategy using Polydimethylsiloxane（PDMS）as an additive both in the perovskite layer and PCBM interlayer to enhance the thermal,light,ambient air,and flexural stability of PSCs.The unencapsulated devices maintained 97%of their initial efficiencies after continuous operation under 1 sun equivalent illumination,60°C and maximum power point（MPP）tracking for 1000 hours,80%of their initial efficiencies exposed in ambient air for 500 h,and after being subjected to 1000 cycles at a bending radius of 8 mm,they retained 85%of their initial efficiencies.Besides,an improved efficiency for p-i-n PSCs of 21.6%（stabilized at 21.3%）was achieved by increasing simultaneously the short-circuit current density and FF up to 24.1 m A cm–2 and 82.8%separately,which is credited to the formation of the hydrogen bond and the Lewis acid-base reciprocity between the PDMS and the perovskite reducing the formamidinium（FA）vacancy defects and uncoordinated Pb defects.（3）Developing a multiple key barrier film strategy based on low-cost metal/metal oxide/polymer（chemically inert bismuth electrode/Al2O3/polyxylene film）to supress the consumption of halide components and the release of gaseous perovskite decomposition products,and the tightly closed system formed by the multilayer barrier can inhibit the degradation of the perovskite and bring the corresponding decomposition reactions to a benign balance.The resulting encapsulated FACs-based PSCs with multiple-barrier maintain 90%of their initial efficiencies after continuous operation at 45℃for 5200 hours and 93%of their maximum power output after continuous operation at 75℃for 1000 hours under 1 sun equivalent white-light LED illumination. |
