Study On Inverted Perovskite Solar Cells Based On Buried Interface Defects And Crystallization Synergistic Regulation

In recent years,inverted perovskite solar cells（PSC）have been widely studied owe to their advantages such as high stability,low temperature solution preparation and easy fabrication of flexible device or tandem cell.So far,the highest certified steady-state power conversion efficiency（PCE）has reached up to 24.53%.However,inverted PSC still need to improve the PCE and device stability due to non-radiative recombination at the interface and poor crystallization process,which hindering their future commercialization.On the other hand,the density of state of defects at the buried bottom interface of perovskite is 1-2 orders of magnitude higher than the bulk phase and top interface,and the subsequent deposition and growth of perovskite have serious negative effects due to poor buried bottom interface characteristics.Therefore,it is criucial to reduce the buried interface defects for suppressed non-radiative recombination and control perovskite crystallization with the orientation directionsto further improve device performance.In this thesis we regulate the buried interface defects and perovskite crystallization process by introducing an interface chemical bridge or constructing concentration gradients,resulting in high-performanceinverted PSC.（1）By introducing N-（2-pyridyl）-trimethylacetamide（NPP）interface layer as a chemical bridge at the perovskite buried interface,the pyridine groups in the NPP conjugated with the phenyl groups in the PTAA throughπ-πstacking interactions to enhance the hole extraction capacity.At the same time,the N-C=O resonance linkage with a lone electron pair dynamically regulated the buried defects through formation strong N⁺=C-O^-···Pb²⁺bonds based on the fast self-adaptive tautomerization between the resonance forms of NPP（N-C=O and N⁺=C-O^-）,which resulted in high-quality perovskite films with low defect densities.The PCE has increased from 17.04%to19.46%.Meanwhile,the long-term photostability has been significantly improved,operating under continuous 1-sun illumination for 2373 hours at～65^oC without loss of PCE.（2）The concentration gradient control strategy is constructed by introducing3-（N,N-dimethyldodecyl ammonium）propane sulfonate（DDAP）molecules at the buried interface and perovsite films to improve crystal growth and promote charge separation and transport.The sulfonic acid group in DDAP molecule could copule with Pb²⁺in the perovskite,increasing the barrier of binding energy and slowing down the crystallization process,which suppressed the random crystal nucleus to adjust their growth along the（100）crystal plan,which has the lowest thermodynamic energy,leading to improved the crystal quality of perovskite.Moreover,the hole transport is further promoted and the energy loss is restrained due to the bulk phase diffusion at the interface at the interface and the perovskite active layer,As the result,the champion PCE has reached approaching 20%.