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.

Tailoring component incorporation for homogenized perovskite solar cells

Deep-level traps at the buried interface of perovskite and energy mismatch problems between the perovskite layer and heterogeneous interfaces restrict the development of ideal homogenized films and efficient perovskite solar cells(PSCs)using the one-step spin-coating method.Here,we strategically employed sparingly soluble germanium iodide as a homogenized bulk in-situ reconstruction inducing material preferentially aggregated at the perovskite buried interface with gradient doping,markedly reducing deep-level traps and withstanding local lattice strain,while minimizing non-radiative recombination losses and enhancing the charge carrier lifetime over 9μs.Furthermore,this gradient doping assisted in modifying the band diagram at the buried interface into a desirable flattened alignment,substantially mitigating the energy loss of charge carriers within perovskite films and improving the carrier extraction equilibrium.As a result,the optimized device achieved a champion power conversion efficiency of 25.24% with a fill factor of up to 84.65%,and the unencapsulated device also demonstrated excellent light stability and humidity stability.This work provides a straightforward and reliable homogenization strategy of perovskite components for obtaining efficient and stable PSCs.

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.