Compositional grading has been widely exploited in highly efficient Cu(In,Ga)Se2, CdTe, GaAs, quantum dot solar cells, and this strategy has the potential to improve the performance of emerging perovskite solar cells. However, realizing and maintaining compositionally graded perovskite absorber from solution processing is challenging. Moreover, the operational stability of graded perovskite sol...

We investigate mixed solvents of N,N-dimethylformamide (DMF) and γ-butyrolactone (GBL) to produce the smooth surface of a perovskite film and uniform crystal domains. This ideal morphology from mixed solvents enhances the power conversion efficiency to over 6% by improving the exciton dissociation efficiency and reducing the recombination loss at both interfaces of PEDOT:PSS/perovskite and pero...

A high-mobility p-type organic semiconductor based on benzodithiophene and diketopyrrolopyrrole with linear alkylthio substituents (BDTS-2DPP) is used as a dual function interfacial layer to modify the interface of perovskite/2,2',7,7'-tetrakis(N,N'-di-p-methoxyphenylamine)-9,9'-spirobifluorene in planar perovskite solar cells. The BDTS-2DPP layer can remarkably passivate the surface defects of...

Perovskite solar cells have received worldwide interests due to swiftly improved efficiency but the poor stability of the perovskite component hampers the device fabrication under normal condition. Herein, we develop a reliable nonstoichiometric acid-base reaction route to stable perovskite films by intermediate chemistry and technology. Perovskite thin-film prepared by nonstoichiometric acid-b...

Organic-inorganic lead halide perovskites are distinct from most other semiconductors because they exhibit characteristics of both electronic and ionic motion. Accurate understanding of the optoelectronic impact of such properties is important to fully optimize devices and be aware of any limitations of perovskite solar cells and broader optoelectronic devices. Here we use a numerical drift-dif...

[1] Aluminum has been reported to have a remarkably strong effect on the thermoelastic properties of MgSiO3 perovskite. However, the sound velocities of aluminous MgSiO3 perovskite have not been previously measured, even though this phase likely dominates most of the chemistry in Earth’s lower mantle. Here we report the first sound velocity measurements on aluminous MgSiO3 perovskite using Bril...

The role of chloride in the MAPbI3-xClx perovskite is still limitedly understood, albeit subjected of much debate. Here, we present a combined angle-resolved X-ray photoelectron spectroscopy (AR-XPS) and first-principles DFT modeling to investigate the MAPbI3-xClx/TiO2 interface. AR-XPS analyses carried out on ad hoc designed bilayers of MAPbI3-xClx perovskite deposited onto a flat TiO2 substra...

Despite the current advancements, yet improving intrinsic structure and external environmental stability of hybrid metal halide perovskite nanomaterials is required for developing efficient perovskite-based devices. Up-to-date, a very attractive method growing and/or embedding nanocrystals within organic polymeric matrices, or into porous inorganic nano/micromaterials (e. g., metal-organic fram...

Perovskite solar cells (PSCs) have great potentials in photovoltaics due to their high power conversion efficiency and low processing cost. PSCs are usually fabricated from PbI2/dimethylformamide solution with some toxic additives, such as N-methyl pyrrolidone and hexamethylphosphoramide. Here, we use an environmental friendly aprotic polar solvent, 1,3-dimethyl-2-imidazolidinone (DMI), to fabr...