Additive Engineering And Interface Engineering Investigation Toward Efficient And Stable 2D And Mixed 2D/3D Perovskite Solar Cells

Organic-inorganic lead halide perovskites with a comparable performance of more than 25%might be potential options for accomplishing cheap photovoltaic electricity.Nevertheless,challenges to the stability and toxicity of lead constitute a serious barrier to the implementation of this innovative technology.Many techniques have been developed to improve the stability of organic-inorganic lead halide perovskite materials.Among them,lowering(2D)and mixing dimensional(2D3D)have been shown to have promising potential.Upcoming 2D perovskite materials have recently received a lot of interest because of their outstanding physicochemical features,with notably increased stability in ambient circumstances due to the hydrophobic character of the bulk organic compounds contained.Nonetheless,the efficiency of 2D perovskites is much lower compared to that of 3D perovskites due to extended exciton binding energy,poor light absorption,and insufficient interlayer charge transport.In addition,two important strategies enhancing the PCE of 2D PSCs have been reported.The first strategy involves expanding the number of inorganic layers in order to get the PCE of 2D PSC closer to that of 3D PSC,although at the disadvantage of stability.In contrast,the second technique,particularly the one susceptible to a specific perpendicular direction of the 2D perovskite layer through the substrate,leads to smooth and fast charge transport in the extracting pathway.This method entails the use of several chemicals that can influence crystal growth.In this regard,a strategy to high-performance 2D perovskite solar cells based on BA2(FAMA)3Pb4I13 employing synergistic impact of co-additives(ammonium thiocyanate(NH4SCN)and hydrochloride acid(HCl))to enable the properly aligned of perovskite film through the substrate,which eventually increases crystallinity and charges transport of 2D perovskite and reduces defect states is presented by us.This co-additive method successfully generates homogenous 2D perovskite films with consistent crystal structures and higher film quality.The champion 2D perovskite device exhibited a photovoltaic performance of 16.45%with an improved Jsc.These results suggest that developing additive engineering might result in remarkably stable and efficient 2D perovskite materials.Incorporating extremely thin 2D perovskite films at the interface between the hole transporting layer(HTL)and the active layer(perovskite layer)is a feasible method for increasing the performance and stability of organic-inorganic hybrid perovskite solar devices.The approach requires spin-coating a solution of spacer cations in IPA on top of a previously created 3D perovskite film to generate a thin 2D perovskite layer.We demonstrate in this work that thin 2D perovskite layers placed atop of 3D perovskite films have a positive impact on the efficiency and stability of the resulting solar cells.Two organic compounds have been used in this work to develop 2D/3D perovskite architectures.Firstly,we constructed a heterostructure 2D/3D via spin-coating of a monoammonium cation based phenylethylammonium bromide(PEABr)solution on top of a 3D double cation perovskite film((F0.6MA0.4)PbI3)(Ruddlesden Popper(RP),).And then,a diammonium cation based on 1,4-Phenylenediamine dihydriodide(PEDA)IPA was spin-coated on top of the 3D triple cation(Cs0.05(FA0.83MA0.17)0.95Pb(I0.83Br0.17))(Dion Jacobson(DJ)),perovskite films toward a 2D/3D mixed-structure.Furthermore,the PSC devices based on optimized 2D/3D hetero-structures display substantial improvements in photovoltaic efficiency due to the passivation of cationic and halide vacancies on the surface of 3D perovskite for better energy level alignments,longer carrier lifetimes,and fewer defects.which facilitate hole transfer and transport to the hole transport layer and reduce interface recombination centers.We achieved tailored 2D thin films on top of 3D,which allowed us to achieve effective efficiencies of 20.54%for double cation perovskite devices with 2D RP and 21.42%for triple cation perovskite devices with 2D DJ.Formamidinium lead iodide(FAPbI3)presents a significant benefit for highperformance perovskite solar cells due to its narrow bandgap and broader absorption.In the ambient environment,however,FAPbI3 can instantaneously transform from the black colored photo-active(α-phase),which is thermodynamically unstable,to the yellow-colored photo-inactive(δ-phase),which is thermodynamically stable,limiting the photovoltaic function and impeding its development for practical applications.In our work,an optimized concentration of co-additives based on propylammoniun chloride(PACl)and ammomiun thiocyanate(NH4SCN)is added to the perovskite precursor solution to stabilize the α-phase of the FAPbI3,control perovskite film formation and passivate defects in perovskite materials.As a result,the perovskite films exhibit exceptional crystallization properties,with a homogenous α-phase,consistent and compact surface shape,improved photo-physical characteristics,low defect density,and long carrier lifetime.Furthermore,the corresponding PSCs have an outstanding PCE of 21.01%,and the device retained 90%of its initial PCE after one month of storage in ambient conditions.Given the fascinating scientific findings provided by this study,as well as the multiple successful solutions published in the field of the halide perovskite society,optoelectronic implementations centered on perovskite materials exhibit promising expectations.