A universal ionic liquid solvent for non-halide lead sources in perovskite solar cells

Replacing lead iodide(PbI_(2))with suitable non-halides lead source has been found to be an effective method to control crystallization and fabricate high-performance perovskite solar cells(PSCs).However,the solubility of non-halide lead sources is highly limited by traditional solvents due to the chemical interaction limitation.Here,we report a series of non-halide lead sources(e.g.,lead acetate(PbAc_(2)),lead sulfate(PbSO_(4)),lead carbonate(PbCO_(3)),lead nitrate(Pb(NO_(3))_(2)),lead formate(Pb(HCOO)_(2))and lead oxalate(PbC_(2)O_(4)))can be well dissolved in an ionic liquid solvent methylammonium acetate(MAAc).We found that the universal strong coordination of C=O with lead ion(Pb^(2+))and the formation of hydrogen bonds were observed in perovskite precursor solution.This allows the dissolution of non-halide lead salts and is able to produce perovskite film with smooth,compact,and full coverage crystal grain.The power conversion efficiency(PCE)of 14.48%,19.21%,and 20.13%in PSCs based on PbSO_(4),PbAc_(2),and PbCO_(3) was achieved,respectively,in the absence of any additives and passivation agents.This study demonstrates the universality of ionic liquid for the preparation of PSCs based on nonhalides lead sources.

大n值准相纯二维卤化物钙钛矿:从材料到器件的工具箱

Despite their excellent environmental stability,low defect density,and high carrier mobility,large-n quasi-two-dimensional halide perovskites(quasi-2DHPs)feature a limited application scope because of the formation of self-assembled multiple quantum wells(QWs)due to the similar thermal stabilities of large-n phases.However,large-n quasi-phase-pure 2DHPs(quasi-PP-2DHPs)can solve this problem perfectly.This review discusses the structures,formation mechanisms,and photoelectronic and physical properties of quasi-PP-2DHPs,summarises the corresponding single crystals,thin films,and heterojunction preparation methods,and presents the related advances.Moreover,we focus on applications of large-n quasi-PP-2DHPs in solar cells,photodetectors,lasers,light-emitting diodes,and field-effect transistors,discuss the challenges and prospects of these emerging photoelectronic materials,and review the potential technological developments in this area.

Efficient and stable Ruddlesden-Popper layered tin-based perovskite solar cells enabled by ionic liquid-bulky spacers

The crucial component,bulky spacers,in two-dimensional Ruddlesden-Popper(2 DRP)layered tin(Sn)perovskites are highly limited by halide ammonium salts,leading to the insufficient control of complex crystallization process due to the limited interaction between bulky spacers and 2 DRP perovskite frameworks.Here,we report an ionic liquid-bulky spacer,butylammounium acetate(BAAc O),for constructing efficient and stable 2 DRP Sn-based perovskite solar cells(PSCs).In contrast to the traditional halide ammonium bulky spacer,butylammounium iodide(BAI),the Ac O^(-)-functional group in BAAc O has a strong interaction with formamidine ions(FA^(+))and Sn2+.The inter-component interaction allows the formation of controllable intermediates for the favorable growth of smooth,dense,and highly oriented perovskite films.A PSC with power conversion efficiency of 10.36%(7.16%for BAI)is achieved,which is the highest report,along with improved stability with~90%retained after~600 h storage in N_(2) atmosphere without any encapsulation.