Improved Photovoltaic Performance And Stability Of Planar Solar Cells Via Upgrading Perovskite Upper Interfaces

Perovskite solar cells（PSCs）have considered the most promising photovoltaic（PV）technology due to their excellent power conversion efficiency（PCE）,simple preparation process,and extensive application prospect.Currently,the certified PCE of PSCs have been increased from the 3.8%to 25.7%.Compared with mesoporous PSCs,planar heterojunction PSCs have been used in flexible,ultrathin,and tandem solar cells due to their simple structure and low-temperature processing.However,the PV performance have reduced due to insufficient light harvesting and hetero-interface carrier losses.In this work,the preparation of efficient and stable planar heterojunction PSCs as the research objective,combined with additive engineering and interface engineering,the development and use of innovative technology,design and construction of the textured absorbers,interface passivation layers,to achieve the simultaneous improvement of the light-trapping capacity,charge transfer dynamics and PV performance.The main contents are as follows:（1）To compensate for the photoelectric losses of planar heterojunction PSCs and achieve a high-efficiency stable PV output,we propose an in situ growth passivation technique to construct high-performance textured absorbers with excellent light-harvesting ability and carrier extraction/transfer efficiency by adding a2-amino-4-chlorophenol（AC）modifier consisting of multiple groups during the growth of textured perovskite.Initially,according to the Ostwald ripening mechanism,the strongly polar dimethylformamide（DMF）was used as the etchant to systematically study its synergistic effect on the morphology evolution,crystallization kinetics,light-trapping capability,and PV loss of textured absorbers.An appropriate amount of DMF induces formamidinium cations（FA⁺）to replace methylammonium cations（MA⁺）in the perovskite lattice while etching the absorber to form a texture configuration,which effectively broadens the spectral absorption range,thus greatly improving the light-trapping capacity and short-circuit current density（Jsc）of planar PSCs.Moreover,owing to the electron-donating nature of the Lewis base,the hydroxyl groups with a higher electron density in AC molecules can better coordinate with Pb²⁺ion defects,which effectively improves the crystallinity of the textured perovskite,thus suppressing the nonradiative recombination and ultimately improving the PV outputs of modified devices,particularly the fill factor（FF）and the open-circuit voltage（Voc）.Thus,the PV performance of the AC-modified planar PSC is significantly better than that of the conventional textured device,with a reverse efficiency of 21.18%and forward efficiency of 20.77%.（2）To balance the top and bottom interface carrier behaviors of perovskite absorbers,the 2D black phosphorus（BP）with high charge mobility was introduced into the interior and upper surface of the perovskite by in-situ coating technology,and a novel 2D-BP@3D-PVK absorber was constructed.The crystallization mechanism of 2D-BP@3D-PVK absorber was analyzed,and the synergistic mechanism between charge dynamics and PV output behavior was elucidated.The-NH₂and-OH groups of 2D-BP have strong interactions with uncoordinated organic cations in perovskite,which can be used as the template for secondary growth of perovskite at the grain boundary,effectively passivating the deep-level defects,inhibiting non-radiation recombination,and thus improving the PV performance of PSCs.In addition,the2D-BP coated on the perovskite can form a fast hole transport channel,optimize the band structure,balance the carrier transport behavior between the top and bottom interfaces of perovskite,thus improving the Voc,FF,and PCE of PSCs,and eliminating hysteresis.Finally,a reverse efficiency of 21.18%and forward efficiency of 20.77%are achieved,respectively,without hysteresis.（3）In order to prepare efficient and stable planar PSCs,in this work,the BP-rGO composite 2D-2D materials with double-side function are introduced into the upper interface of perovskite absorbers by interfacial deposition technology.The mechanism of BP-rGO passivation is systematically analyzed,and the synergistic mechanism between the upper interface modification of perovskite on charge transfer dynamics,PV output,and stability of planar PSCs is elucidated.The BP-rGO with double-sided function shows excellent targeted adsorption effect through ion interaction,which inhibits non-radiative recombination,accelerates interface carrier extraction/migration/collection,and thus improving the Jsc,FF and PCE of the PSCs.Moreover,the coordination between rGO and spiro-OMe TAD prevents the erosion of perovskite by external factors,thus improving the stability of the PSCs.In addition,the PV performance and stability of PSCs is improved due to the enhanced the hole transport behavior.Finally,we obtained a planar heterojunction PSC with a PCE of about 21.98%,and the PSCs still maintained more than 90%of initial PCE under continuous illumination for 250 min,showing excellent PV output stability.