Crystallization and Orientation Modulation Enable Highly Efficient Doctor-Bladed Perovskite Solar Cells

With the rapid rise in perovskite solar cells(PSCs)performance,it is imperative to develop scalable fabrication techniques to accelerate potential commercialization.However,the power conversion efficiencies(PCEs)of PSCs fabricated via scalable two-step sequential deposition lag far behind the state-of-the-art spin-coated ones.Herein,the additive methylammonium chloride(MACl)is introduced to modulate the crystallization and orientation of a two-step sequential doctorbladed perovskite film in ambient conditions.MACl can significantly improve perovskite film quality and increase grain size and crystallinity,thus decreasing trap density and suppressing nonradiative recombination.Meanwhile,MACl also promotes the preferred face-up orientation of the(100)plane of perovskite film,which is more conducive to the transport and collection of carriers,thereby significantly improving the fill factor.As a result,a champion PCE of 23.14%and excellent longterm stability are achieved for PSCs based on the structure of ITO/SnO_(2)/FA_(1-x)MA_xPb(I_(1-y)Br_y)_3/Spiro-OMeTAD/Ag.The superior PCEs of 21.20%and 17.54%are achieved for 1.03 cm~2 PSC and 10.93 cm~2 mini-module,respectively.These results represent substantial progress in large-scale two-step sequential deposition of high-performance PSCs for practical applications.

Ultrathin Metal-Organic Framework Nanosheets-Derived Yolk-Shell Ni_(0.85)Se@NC with Rich Se-Vacancies for Enhanced Water Electrolysis

We present a controlled fabrication of selective ultrathin metal-organic framework(MOF)nanosheets as preassembling platforms,yolk-shell structured with a few-layered N-doped carbon(NC)shell-encapsulated Ni_(0.85)Se core(denoted as Ni_(0.85)Se@NC)via an oriented phase modulation(OPM)strategy.The ultrathin nature of the MOF nanosheets gave rise to the modification of structure at the electronic level with abundant Se-vacancies and effective electronic coupling via an Ni-N_(x) coordination at the interface between the Ni0.85Se core and NC shell.The Ni0.85Se@NC obtained exhibited low overpotentials for both oxygen evolution reaction(OER;300 mV)and hydrogen evolution reaction(HER;157 mV)at 10 mA·cm^(−2) under an alkaline condition,outperforming their corresponding bulk MOF-derived counterparts.By exploiting Ni_(0.85)Se@NC as anode and cathode catalysts,a low cell voltage of 1.61 V was achieved by performing alkaline water electrolysis.Remarkably,it also reached a high activity in natural seawater(pH=7.98)and simulated seawater(pH=7.86)electrolytes,even surpassing integrated Pt/C-RuO_(2)/CC electrodes.Density functional theory(DFT)studies illustrated that abundant Se-vacancies effectively regulated the electronic structure of Ni_(0.85)Se@NC by accelerating electron transfer from Ni to N atoms at the interface,and thus,enabling the Ni_(0.85)Se@NC to attain a near-optimal electronic configuration that stimulated ideal adsorption-free energy toward key reaction intermediates.