Solvent-dripping modulated 3D/2D heterostructures for high-performance perovskite solar cells.

The controlled growth of two-dimensional (2D) perovskite atop three-dimensional (3D) perovskite films reduces interfacial recombination and impedes ion migration, thus improving the performance and stability of perovskite solar cells (PSCs). Unfortunately, the random orientation of the spontaneously formed 2D phase atop the pre-deposited 3D perovskite film can deteriorate charge extraction owing to energetic disorder, limiting the maximum attainable efficiency and long-term stability of the PSCs. Here, we introduce a meta-amidinopyridine ligand and the solvent post-dripping step to generate a highly ordered 2D perovskite phase on the surface of a 3D perovskite film.

On the Conformation of Dimeric Acceptors and Their Polymer Solar Cells with Efficiency over 18 .

The determination of molecular conformations of oligomeric acceptors (OAs) and their impact on molecular packing are crucial for understanding the photovoltaic performance of their resulting polymer solar cells (PSCs) but have not been well studied yet. Herein, we synthesized two dimeric acceptor materials, DIBP3F-Se and DIBP3F-S, which bridged two segments of Y6-derivatives by selenophene and thiophene, respectively. Theoretical simulation and experimental 1D and 2D NMR spectroscopic studies prove that both dimers exhibit O-shaped conformations other than S- or U-shaped counter-ones.

Efficient and stable perovskite-silicon tandem solar cells through contact displacement by MgF.

The performance of perovskite solar cells with inverted polarity (p-i-n) is still limited by recombination at their electron extraction interface, which also lowers the power conversion efficiency (PCE) of p-i-n perovskite-silicon tandem solar cells. A MgF interlayer with thickness of ~1 nanometer at the perovskite/C interface favorably adjusts the surface energy of the perovskite layer through thermal evaporation, which facilitates efficient electron extraction and displaces C from the perovskite surface to mitigate nonradiative recombination. These effects enable a champion open-circuit voltage of 1.

Probing Ultrafast Interfacial Carrier Dynamics in Metal Halide Perovskite Films and Devices by Transient Reflection Spectroscopy.

Interfaces in metal halide perovskite (MHP) solar cells cause carrier recombination and thereby reduce their power conversion efficiency. Here, ultrafast (picosecond to nanosecond) transient reflection (TR) spectroscopy has been used to probe interfacial carrier dynamics in thin films of the reference MHP MAPbI and state-of-the-art (CsMAFA)Pb(BrI) (CsFAMA). First, MAPbI films in contact with fullerene-based charge extraction layers (CTLs) in the presence and absence of LiF used as an interlayer (ITL) were studied.

Tin Oxide Electron-Selective Layers for Efficient, Stable, and Scalable Perovskite Solar Cells.

Perovskite solar cells (PSCs) have become a promising photovoltaic (PV) technology, where the evolution of the electron-selective layers (ESLs), an integral part of any PV device, has played a distinctive role to their progress. To date, the mesoporous titanium dioxide (TiO )/compact TiO stack has been among the most used ESLs in state-of-the-art PSCs. However, this material requires high-temperature sintering and may induce hysteresis under operational conditions, raising concerns about its use toward commercialization.

Lewis-Acid Doping of Triphenylamine-Based Hole Transport Materials Improves the Performance and Stability of Perovskite Solar Cells.

Highly efficient perovskite solar cells (PSCs) fabricated in the classic n-i-p configuration generally employ triphenylamine-based hole-transport layers (HTLs) such as spiro-OMeTAD, PTAA, and poly-TPD. Controllable doping of such layers has been critical to achieve increased conductivity and high device performance. To this end, LiTFSI/tBP doping and subsequent air exposure is widely utilized.

The Effect of Methylammonium Iodide on the Supersaturation and Interfacial Energy of the Crystallization of Methylammonium Lead Triiodide Single Crystals.

It is very important to study the crystallization of hybrid organic-inorganic perovskites because their thin films are usually prepared from solution. The investigation on the growth of perovskite films is however limited by their polycrystallinity. In this work, methylammonium lead triiodide single crystals grown from solutions with different methylammonium iodide (MAI):lead iodide (PbI ) ratios were investigated.

Factors Influencing the Mechanical Properties of Formamidinium Lead Halides and Related Hybrid Perovskites.

The mechanical properties of formamidinium lead halide perovskites (FAPbX , X=Br or I) grown by inverse-temperature crystallization have been studied by nanoindentation. The measured Young's moduli (9.7-12.

Efficiency enhancement of planar perovskite solar cells by adding zwitterion/LiF double interlayers for electron collection.

Double interlayers consisting of a zwitterionic small molecule layer and a LiF layer were introduced between the electron transport layer and the cathode of perovskite solar cells. The double interlayers improve the photovoltaic efficiency to 13.2%, which is higher than that of control devices without the double interlayer (9.