Additive Engineering for Stable and Efficient Dion-Jacobson Phase Perovskite Solar Cells

Because of their better chemical stability and fascinating anisotropic characteristics,Dion-Jacobson(DJ)-layered halide perovskites,which owe crystallographic two-dimensional structures,have fascinated growing attention for solar devices.DJ-layered halide perovskites have special structural and photoelectronic features that allow the van der Waals gap to be eliminated or reduced.DJ-layered halide perovskites have improved photophysical characteristics,resulting in improved photovoltaic performance.Nevertheless,owing to the nature of the solution procedure and the fast crystal development of DJ perovskite thin layers,the precursor compositions and processing circumstances can cause a variety of defects to occur.The application of additives can impact DJ perovskite crystallization and film generation,trap passivation in the bulk and/or at the surface,interface structure,and energetic tuning.This study discusses recent developments in additive engineering for DJ multilayer halide perovskite film production.Several additive-assisted bulk and interface optimization methodologies are summarized.Lastly,an overview of research developments in additive engineering in the production of DJ-layered halide perovskite solar cells is offered.

Formamidinium-incorporated Dion-Jacobson phase 2D perovskites for highly efficient and stable photovoltaics

Dion-Jacobson phase two-dimensional(DJ 2D)perovskites,recently attracting considerable interests,exhibit excellent environmental stability and structural tunability,but their solar cells still offer unsatisfactory power conversion efficiencies(PCEs).Herein,we develop DJ 2D perovskites employing formamidinium(FA+)as a ternary cation in the perovskite cages((PDA)(FA)x(MA)3-xPb4 I13,χ=0,0.15,0.3 and 0.6,PDA=1,3-propanediammonium)for highly efficient and stable perovskite solar cells(PSCs).We found that the DJ 2D perovskite with a 10%FA+fraction presents improved crystallinity,preferred vertical orientation,and longer charge carrier lifetime compared to that without FA+doping.As a result,the FAdoped DJ 2D PSCs exhibit a champion PCE of 14.74%with superior device stability.The unencapsulated devices sustain over 92%of its initial PCE after storage at a constant relative humidity(RH)of 65%for 6000 h,90%by heat at 85℃in air for 800 h,and 94%under 1-sun illumination for 5000 h.These findings demonstrate that the incorporation of FA cation into the DJ 2D perovskite is a promising strategy to develop highly efficient and stable DJ 2D PSCs.

Long-term Stable 2D Dion-Jacobson Phase Perovskite Photodiode with Low Dark Current and High On/off Ratio

A two-dimensional(2D)organic-inorganic hybrid perovskite(OIHP)material is considered as a promising candidate for a long-term stable photodetector owing to its outstanding phase and environmental stability.Herein,we demonstrate a perovskite photodiode based on the DJ phase 2D perovskite(PDA)(MA)_(n-1)Pb_(n)I_(3n+1)(where PDA is 1,3-propylenediamine,MA is methylamine,nominal n=4).The best-performance device exhibits a high detectivity of 4.57×10^(11) Jones,a responsivity of 0.25 A·W^(-1) at 480 nm,a low dark current density of 9.60×10^(-4) mA cm^(-2),and a remarkable on/off ratio of 3.10×10^(5).The unencapsulated device can maintain 95%of the initial photocurrent density after 90 days under an ambient atmosphere with relative humidity(RH)of 65%,demonstrating its improved stability than the 3D counterpart.The excellent stability of the photodiode based on 2D perovskite promises its bright commercial application ftiture.

Large bandgap oscillations in two-dimensional Dion–Jacobson phase perovskites caused by coherent longitudinal acoustic phonons [Invited]

Two-dimensional Dion–Jacobson(D-J)phase perovskites are prospective photovoltaic and optoelectronic materials.To study their mechanical properties and carrier-lattice interactions,we conduct femtosecond spectroscopic experiments on the films of a D-J perovskite.After optical excitation,a∼33 meV bandgap oscillation is observed in the film by transient absorption spectroscopy.With the help of transient reflection methods,we reveal that the oscillation originates from the transport of coherent longitudinal acoustic phonons through the film.Large bandgap oscillation indicates a strong coupling between carriers and lattice,and significant bandgap modulation by strains in D-J perovskites.

氟化间隔阳离子调控能量传输实现二维D-J CsPbI3太阳能电池记录效率

二维CsPbI_(3)钙钛矿太阳能电池由于出色的稳定性受到了广泛关注.然而,二维结构中有机阳离子与无机平面之间复杂的相互作用限制了其光电转换效率的进一步提高.为此,作者从功能化有机阳离子的角度出发,将含氟间隔阳离子应用于构筑二维D-J CsPbI_(3)器件.首先借助第一性原理计算分析了二维钙钛矿结构中功能化有机阳离子与无机平面的耦合情况,揭示了含氟有机阳离子能够增加二维结构中的介电常数,减小激子结合能,并优化能量传输路径.进一步从实验上证明了含氟有机阳离子对增加二维钙钛矿薄膜的结晶度、降低缺陷态密度,优化载流子的提取与传输等过程具有积极意义.基于此,本文实现了二维D-J CsPbI_(3)器件的记录效率以及良好的运行稳定性.本工作从优化二维D-J CsPbI_(3)结构中能量传输路径的角度出发,思考了器件性能与材料微观结构之间的关系,为二维CsPbI_(3)器件性能的进一步发展提供了新的思路.