Enhanced cation interaction in perovskites for efficient tandem solar cells with silicon.

To achieve the full potential of monolithic perovskite/silicon tandem solar cells, crystal defects and film inhomogeneities in the perovskite top cell must be minimized. We discuss the use of methylenediammonium dichloride as an additive to the perovskite precursor solution, resulting in the incorporation of in situ-formed tetrahydrotriazinium (THTZ-H) into the perovskite lattice upon film crystallization. The cyclic nature of the THTZ-H cation enables a strong interaction with the lead octahedra of the perovskite lattice through the formation of hydrogen bonds with iodide in multiple directions.

Double-side 2D/3D heterojunctions for inverted perovskite solar cells.

Defects at the top and bottom interfaces of three-dimensional (3D) perovskite photoabsorbers diminish the performance and operational stability of perovskite solar cells owing to charge recombination, ion migration and electric-field inhomogeneities. Here we demonstrate that long alkyl amine ligands can generate near-phase-pure 2D perovskites at the top and bottom 3D perovskite interfaces and effectively resolve these issues. At the rear-contact side, we find that the alkyl amine ligand strengthens the interactions with the substrate through acid-base reactions with the phosphonic acid group from the organic hole-transporting self-assembled monolayer molecule, thus regulating the 2D perovskite formation.

Efficient and reliable encapsulation for perovskite/silicon tandem solar modules.

Perovskite/silicon tandem solar cells have a tremendous potential to boost renewable electricity production thanks to their very high performance combined with promising cost structure. However, for actual field deployment, any solar cell technology needs to be assembled into modules, where the associated processes involve several challenges that may affect both the performance and stability of the devices. For instance, due to its hygroscopic nature, ethylene vinyl acetate (EVA) is incompatible with perovskite-based photovoltaics.

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.

Beyond Perovskite Solar Cells: Tellurium Iodide as a Promising Light-Absorbing Material for Solution-Processed Photovoltaic Application.

Searching new light-absorbing materials to replace toxic lead halide in solar cells is very important and highly desirable. In this research, we firstly demonstrated that tellurium iodide (TeI ) could be used as a light-absorbing material in solar cells due to its suitable optical band gap and the active lone-pair electron orbital in Te . The best power conversion efficiency (PCE=3.

Imide-Fused Diazatetracenes: Synthesis, Characterization, and Application in Perovskite Solar Cells.

A series of imide-fused diazatetracenes were synthesized via Buchwald-Hartwig C-N coupling with a highly active palladium source. The introduction of an imide segment effectively lowers the LUMO levels compared with that of unsubstituted diazatetracene. By adjusting the alkyl chains of the diazatetracenes, different solid-state packings were achieved, resulting in distinct photoluminescent behaviors.

Molecular Aggregation of Naphthalene Diimide(NDI) Derivatives in Electron Transport Layers of Inverted Perovskite Solar Cells and Their Influence on the Device Performance.

One of key factors to design applicable electron transport layers (ETLs) for perovskite solar cells is the morphology of ETLs since a good morphology would help to facilitate the carrier transport at two interfaces (perovskite\ETL and ETL\cathode). However, one drawback of most organic ETL small molecules is the internal undesired accumulation, which would cause the formation of inappropriate morphology and rough ETL surface. Here, by elaborately designing the side chains of NDI derivatives, the molecular interaction could be modified to achieve the aggregation in different degrees, which would eventually affect the accumulation of molecules and surface qualities of ETLs.

Influences of Structural Modification of Naphthalenediimides with Benzothiazole on Organic Field-Effect Transistor and Non-Fullerene Perovskite Solar Cell Characteristics.

Developing air-stable high-performance small organic molecule-based n-type and ambipolar organic field-effect transistors (OFETs) is very important and highly desirable. In this investigation, we designed and synthesized two naphthalenediimide (NDI) derivatives (NDI-BTH1 and NDI-BTH2) and found that introduction of 2-(benzo[]thiazol-2-yl) acetonitrile groups at the NDI core position gave the lowest unoccupied molecular orbital (LUMO; -4.326 eV) and displayed strong electron affinities, suggesting that NDI-BTH1 might be a promising electron-transporting material (i.

Unexpected Synthesis, Properties, and Nonvolatile Memory Device Application of Imidazole-Fused Azaacenes.

The unexpected synthesis and characterization of imidazole-fused azaacenes are presented. Their optical and electrochemical properties have been investigated and compared with these of previously reported imidazole-fused azaacenes. Application of these two imidazole-fused azaacenes in memory devices showed distinctly different resistive behaviors.

Recent Progress in Organic Electron Transport Materials in Inverted Perovskite Solar Cells.

Organic n-type materials (e.g., fullerene derivatives, naphthalene diimides (NDIs), perylene diimides (PDIs), azaacene-based molecules, and n-type conjugated polymers) are demonstrated as promising electron transport layers (ETLs) in inverted perovskite solar cells (p-i-n PSCs), because these materials have several advantages such as easy synthesis and purification, tunable frontier molecular orbitals, decent electron mobility, low cost, good solubility in different organic solvents, and reasonable chemical/thermal stability.

Efficient Inverted Perovskite Solar Cells by Employing N-Type (D-A -D-A ) Polymers as Electron Transporting Layer.

It is highly desirable to employ n-type polymers as electron transporting layers (ETLs) in inverted perovskite solar cells (PSCs) due to their good electron mobility, high hydrophobicity, and simplicity of film forming. In this research, the capability of three n-type donor-acceptor -donor-acceptor (D-A -D-A ) conjugated polymers (pBTT, pBTTz, and pSNT) is first explored as ETLs because these polymers possess electron mobilities as high as 0.92, 0.