Lattice Matching Anchoring of Hole-Selective Molecule on Halide Perovskite Surfaces for n-i-p Solar Cells.

Exploiting the self-assembled molecules (SAMs) as hole-selective contacts has been an effective strategy to improve the efficiency and long-term stability of perovskite solar cells (PSCs). Currently, research works are focusing on constructing SAMs on metal oxide surfaces in p-i-n PSCs, but realizing a stable and dense SAM contact on halide perovskite surfaces in n-i-p PSCs is still challenging. In this work, the hole-selective molecule for n-i-p device is developed featuring a terephthalic methylammonium core structure that possesses double-site anchoring ability and a matching diameter (6.

Solution-Crystalized AgBiS Films for Solar Cells Generating a Photo-Current Density Over 31 mA cm.

In response to the toxic heavy metal absorbers in perovskite solar cells (PSCs), this work focuses on the development of an environmentally friendly simple solution-processed infrared (IR) absorber. In this work, a simple solution-crystallized IR-absorbing AgBiS film is reported by spin-coating silver, bismuth nitrates, and thiourea dissolved in dimethylformamide (DMF) to produce thick AgBiS film. Extensive optimization of the precursor concentrations thicknesses and conductive substrates used allow for obtaining 250 nm AgBiS film with different crystal sizes.

Investigation of the Temperature Coefficients of Perovskite Solar Cells for Application in High-Temperature Environments.

Perovskite solar cells are actively investigated for their potential as highly efficient and cost-effective photovoltaic devices. However, a significant challenge in their practical application is enhancing their durability. Particularly, these cells are expected to be subjected to heating by sunlight in real-world operating environments.

Zwitterion Dual-Modification Strategy for High-Quality NiO and Perovskite Films for Solar Cells.

Nickel oxide (NiO) has been limited in use as a hole transport layer for its low conduction, surface defects, and redox reactions with the perovskite layer. To address these issues, the incorporation of zwitterion L-tryptophan (Trp) is proposed at the NiO/Trp interface. The carboxyl group of Trp effectively passivates the surface positive defects of NiO, thereby improving its optical and electrical properties.

Perovskite Solar Cells Based on Polymerized Chlorophyll Films as Environmentally Friendly Hole-Transporting Layers.

Hole-transporting layers (HTLs) play a crucial role in the performance of inverted, p-i-n perovskite solar cells (PSCs). Chlorophylls (Chls) are naturally abundant organic photoconductors on earth, with good charge carrier mobility and appropriate Fermi energy levels that make them promising candidates for use in photovoltaic devices. However, Chls films prepared using the solution method exhibit lower carrier mobility compared to other organic polymer films, which limits their application in PSCs.

Organic Dye/CsAgBiBr Double Perovskite Heterojunction Solar Cells.

The photovoltaic performance of CsAgBiBr perovskite is limited by its light-harvesting ability owing to its broad bandgap. Here, we introduced three indoline dyes, D102, D131, and D149, to sensitize the TiO electron transport layer that was employed in the CsAgBiBr perovskite solar cells (PSCs). The perovskite-indoline dye hybrid cells worked with higher power conversion efficiencies (PCEs) than the corresponding dye-sensitized solar cells and the PSC.

Ionic Liquid-Assisted MAPbI Nanoparticle-Seeded Growth for Efficient and Stable Perovskite Solar Cells.

With the rapid improvement of perovskite solar cells (PSCs), long-life operational stability has become a major requirement for their commercialization. In this work, we devised a pristine cesium-formamidinium-methylammonium (termed as CsFAMA) triple-cation-based perovskite precursor solution into the ionic liquid (IL)-assisted MAPbI nanoparticles (NPs) through a seeded growth approach in which the host IL-assisted MAPbI NPs remarkably promote high-quality perovskite films with large single-crystal domains, enhancing the device performance and stability. The power conversion efficiency (PCE) of the MAPbI NP-seeded growth of MAPbI NPs/CsFAMA-based PSCs is as high as 19.

Chlorophyll Derivative-Sensitized TiO Electron Transport Layer for Record Efficiency of CsAgBiBr Double Perovskite Solar Cells.

The power conversion efficiency (PCE) of CsAgBiBr-based perovskite solar cells (PSCs) is still low owing to the inherent defects of CsAgBiBr films. Herein, we demonstrate a carboxy-chlorophyll derivative (C-Chl)-sensitized mesoporous TiO (m-TiO) film as an electron transport layer (ETL) to enhance and extend the absorption spectrum of CsAgBiBr-based PSCs. The C-Chl-based device achieves a significantly improved PCE, exceeding 3% for the first time, with an increase of 27% in short-circuit current density.

Quantum cutting-induced near-infrared luminescence of Yb and Er in a layer structured perovskite film.

Quantum cutting is an attractive optical phenomenon where one high-energy photon is converted into two low-energy photons, resulting in photoluminescence quantum yields (PLQYs) above 100%. In this report, we demonstrate a novel approach to enhance the quantum cutting energy transfer from an all-inorganic perovskite (CsPbCl) to ytterbium (Yb) and erbium (Er) ions as near-infrared (NIR) emitters by using the highly orientated crystalline film. Yb ions are fixed in the neighborhood of the CsPbCl lattice by preparing a one-to-one layer arrangement consisting of quasi-2D CsPbCl perovskite and Yb layers.

Cesium Acetate-Induced Interfacial Compositional Change and Graded Band Level in MAPbI Perovskite Solar Cells.

Compositional engineering and interfacial modifications have played pivotal roles in the accomplishment of high-efficiency perovskite solar cells (PSCs). Different interfaces in the PSCs influence the performance remarkably either by altering the crystallization of the active material or shifting the energy levels or improving the electrical contact. This work reports how a thin layer of cesium acetate on the TiO electron transport layer (ETL) induces generation of a PbI-rich methylammonium lead iodide (MAPbI) composition at the ETL/MAPbI interface, which downshifts the conduction band level of MAPbI to create an energy level gradient favorable for carrier collection, resulting in higher photocurrent, fill factor, and overall power conversion efficiency.

Full Efficiency Recovery in Hole-Transporting Layer-Free Perovskite Solar Cells With Free-Standing Dry-Carbon Top-Contacts.

Carbon-based top electrodes for hole-transporting-layer-free perovskite solar cells (PSCs) were made by hot press (HP) transfer of a free-standing carbon-aluminum foil at 100°C and at a pressure of 0.1 MPa on a methylammonium lead iodide (MAPbI) layer. Under these conditions, the perovskite surface was preserved from interaction with the solvent.

Over 1.4 V for Amorphous Tin-Oxide-Based Dopant-Free CsPbIBr Perovskite Solar Cells.

CsPbIBr perovskite solar cells have attracted much attention because of the rapid development in their efficiency and their great potential as a top cell of tandem solar cells. However, the outputs observed so far in most cases are far from that desired for a top cell. Up to now, with various kinds of treatments, the reported champion is only 1.

Synthesis, optoelectronic properties and applications of halide perovskites.

Halide perovskites have emerged as a class of most promising and cost-effective semiconductor materials for next generation photoluminescent, electroluminescent and photovoltaic devices. These perovskites have high optical absorption coefficients and exhibit narrow-band bright photoluminescence, in addition to their halide-dependent tuneable bandgaps, low exciton binding energies, and long-range carrier diffusion. These properties make these perovskites superior to classical semiconductors such as silicon.

Low-Temperature Synthesized Nb-Doped TiO Electron Transport Layer Enabling High-Efficiency Perovskite Solar Cells by Band Alignment Tuning.

An Nb-doped TiO (Nb-TiO) film comprising a double structure stacked with a bottom compact layer and top mesoporous layers was synthesized by treating a Ti precursor-coated substrate using a one-step low-temperature steam-annealing (SA) method. The SA-based Nb-TiO films possess high crystallinity and conductivity, and that allows better control over the conduction band (CB) of TiO for the electron transport layer (ETL) of the perovskite solar cells by the Nb doping level. Optimization of power conversion efficiency (PCE) for the Nb-TiO-based ETL was combined with the CB level tuning of the mixed-halide perovskite by changing the Br/I ratio.

Sensitized Yb Luminescence in CsPbCl Film for Highly Efficient Near-Infrared Light-Emitting Diodes.

Near-infrared (NIR) light emitting diodes (LEDs) with the emission wavelength over 900 nm are useful in a wide range of optical applications. Narrow bandgap NIR emitters have been widely investigated using organic compounds and colloidal quantum dots. However, intrinsically low charge mobility and luminescence efficiency of these materials limit improvement of the external quantum efficiency (EQE) of NIR LEDs, which is far from practical applications.

Photomultiplying Visible Light Detection by Halide Perovskite Nanoparticles Hybridized with an Organo Eu Complex.

A molecular layer of an organo europium (Eu) complex was hybridized with the surface of halide perovskite (MAPbI) nanocrystals to control charge transport between photoexcited perovskites and a metal electrode. A thin hybridized nanocrystalline film was found to cause an efficient photomultiplication reaction based on hole accumulation at photoexcited perovskite nanoparticles and charge tunneling across the Eu complex molecules under application of a low external bias (-0.5 V).

Performance enhancement of AgBiI solar cells by modulating a solvent-mediated adduct and tuning remnant BiI in one-step crystallization.

We modulated a solvent-mediated adduct for one-step crystallization of lead-free AgBi2I7 at a lower temperature (90 °C) and to obtain remnant BiI3 by controlling the nature of the substrate and precursor concentration. This eventually resulted in remarkable enhancement in the power conversion efficiency, reaching 2.12%, and the long-term stability of AgBi2I7 solar cells towards light, heat and humidity.

Halide Perovskite Photovoltaics: Background, Status, and Future Prospects.

The photovoltaics of organic-inorganic lead halide perovskite materials have shown rapid improvements in solar cell performance, surpassing the top efficiency of semiconductor compounds such as CdTe and CIGS (copper indium gallium selenide) used in solar cells in just about a decade. Perovskite preparation via simple and inexpensive solution processes demonstrates the immense potential of this thin-film solar cell technology to become a low-cost alternative to the presently commercially available photovoltaic technologies. Significant developments in almost all aspects of perovskite solar cells and discoveries of some fascinating properties of such hybrid perovskites have been made recently.

Tolerance of Perovskite Solar Cell to High-Energy Particle Irradiations in Space Environment.

Materials to be used in the space environment have to withstand extreme conditions, particularly with respect to cosmic particle irradiation. We report robust stability and high tolerance of organolead trihalide perovskite solar cells against high-fluence electron and proton beams. We found that methylammonium and formamidinium-based lead iodide perovskite solar cells composed of TiO and a conductive polymer, as electron and hole transport materials, can survive against accumulated dose levels up to 10 and 10particles/cm of electrons (1 MeV) and protons (50 KeV), respectively, which are known to completely destroy crystalline Si-, GaAS-, and InGaP/GaAs-based solar cells in spacecraft.

Thiocyanate Containing Two-Dimensional Cesium Lead Iodide Perovskite, CsPbI(SCN): Characterization, Photovoltaic Application, and Degradation Mechanism.

We explored thiocyanate (SCN)-based two-dimensional (2D) organometal lead halide perovskite families toward photovoltaic applications. Using an SCN axial ligand and various cation species, we examined AA'PbI(SCN)-type 2D perovskite by replacing the cation species (AA') between methylammonium (MA), formamidinium (FA), and cesium. Among various cation compositions, only all-inorganic cesium-based SCN perovskite, CsPbI(SCN), film showed high thermal stability compared to known 2D perovskites.

Invalidity of Band-Gap Engineering Concept for Bi Heterovalent Doping in CsPbBr Halide Perovskite.

Heterovalent CsPbBr doping with Bi results in a significant red shift of the optical absorption of both single-crystal and powdered samples. The results of low-temperature (3.6 K) photoluminescence studies of perovskite single crystals indicate that the position of the excitonic luminescence peak remains unaffected by Bi doping that, in turn, infers that the band gap of Bi-doped perovskite is not changed as well.

Stability and Degradation in Hybrid Perovskites: Is the Glass Half-Empty or Half-Full?

Methylammonium lead iodide (CHNHPbI) is an extensively used perovskite material with a remarkable potential for solar energy conversion. Despite its high photovoltaic efficiency, the material suffers from fast degradation when aging in atmospheric conditions and/or under sunlight. Here we review the principal degradation mechanisms of CHNHPbI, focusing on the thermodynamic, environmental and polymorphic parameters that impact the stability of the material.

Spontaneous Synthesis of Highly Crystalline TiO Compact/Mesoporous Stacked Films by a Low-Temperature Steam-Annealing Method for Efficient Perovskite Solar Cells.

Highly crystalline TiO nanostructured films were synthesized by a simple steam treatment of a TiCl precursor film under a saturated water vapor atmosphere at 125 °C, here referred to as the steam-annealing method. In a single TiO film preparation step, a bilayer structure comprising a compact bottom layer and a mesoporous surface layer was formed. The mesoporous layer was occupied by bipyramidal nanoparticles, with a composite phase of anatase and brookite crystals.