Achieving high solar-to-hydrogen (STH) efficiency concomitant with long-term durability using low-cost, scalable photo-absorbers is a long-standing challenge. Here we report the design and ...fabrication of a conductive adhesive-barrier (CAB) that translates >99% of photoelectric power to chemical reactions. The CAB enables halide perovskite-based photoelectrochemical cells with two different architectures that exhibit record STH efficiencies. The first, a co-planar photocathode-photoanode architecture, achieved an STH efficiency of 13.4% and 16.3 h to t
, solely limited by the hygroscopic hole transport layer in the n-i-p device. The second was formed using a monolithic stacked silicon-perovskite tandem, with a peak STH efficiency of 20.8% and 102 h of continuous operation before t
under AM 1.5G illumination. These advances will lead to efficient, durable, and low-cost solar-driven water-splitting technology with multifunctional barriers.
We present near-ideal axisymmetric numerically optimized spline concentrators (OSCs) which outperform the compound parabolic concentrator (CPC). By perturbing the profile of the revolved CPC by a ...variable-offset spline defined in tangent-normal space, we show that ray rejection can be reduced to nearly half of that of the CPC, without increasing concentrator length. The resulting OSCs achieve acceptance efficiencies as high as 99.3% for an acceptance angle of 45°, the highest reported for any finite-length CPC-like light concentrator. A set of design curves is presented which can be used to generate near "best-form" OSCs for any acceptance angle in the range 10° to 45°.
Three-dimensional (3D) organic–inorganic lead halide perovskites have emerged in the past few years as a promising material for low-cost, high-efficiency optoelectronic devices. Spurred by this ...recent interest, several subclasses of halide perovskites such as two-dimensional (2D) halide perovskites have begun to play a significant role in advancing the fundamental understanding of the structural, chemical, and physical properties of halide perovskites, which are technologically relevant. While the chemistry of these 2D materials is similar to that of the 3D halide perovskites, their layered structure with a hybrid organic–inorganic interface induces new emergent properties that can significantly or sometimes subtly be important. Synergistic properties can be realized in systems that combine different materials exhibiting different dimensionalities by exploiting their intrinsic compatibility. In many cases, the weaknesses of each material can be alleviated in heteroarchitectures. For example, 3D-2D halide perovskites can demonstrate novel behavior that neither material would be capable of separately. This review describes how the structural differences between 3D halide perovskites and 2D halide perovskites give rise to their disparate materials properties, discusses strategies for realizing mixed-dimensional systems of various architectures through solution-processing techniques, and presents a comprehensive outlook for the use of 3D-2D systems in solar cells. Finally, we investigate applications of 3D-2D systems beyond photovoltaics and offer our perspective on mixed-dimensional perovskite systems as semiconductor materials with unrivaled tunability, efficiency, and technologically relevant durability.
We present a design strategy for fabricating ultrastable phase-pure films of formamidinium lead iodide (FAPbI 3 ) by lattice templating using specific two-dimensional (2D) perovskites with FA as the ...cage cation. When a pure FAPbI 3 precursor solution is brought in contact with the 2D perovskite, the black phase forms preferentially at 100°C, much lower than the standard FAPbI 3 annealing temperature of 150°C. X-ray diffraction and optical spectroscopy suggest that the resulting FAPbI 3 film compresses slightly to acquire the (011) interplanar distances of the 2D perovskite seed. The 2D-templated bulk FAPbI 3 films exhibited an efficiency of 24.1% in a p-i-n architecture with 0.5–square centimeter active area and an exceptional durability, retaining 97% of their initial efficiency after 1000 hours under 85°C and maximum power point tracking.
Editor’s summary A two-dimensional perovskite template kinetically traps the photoactive black phase of formamidinium lead iodide (FAPbI3) from solution. Sidhik et al . show that a Ruddlesden-Popper perovskite, A′ 2 FAPb 2 I 7 , where the A′ cation can be butylammonium or pentylammonium, converts a precursor solution into black-phase FAPbI 3 at 100°C, a temperature at which the inactive yellow phase would normally be more stable. The template imparts compressive strain to the black phase. Solar cells had a power conversion efficiency of 24.1% for a 0.5-square-centimeter active area and maintained 97% of their efficiency for 1000 hours at 85°C under maximum power point tracking. —Phil Szuromi
Semitransparent perovskite solar cells (ST-PSCs) have emerged as an exciting prospect due to their applications in future smart buildings. Semitransparency is typically realized through the use of ...wide bandgap perovskite materials with a reduced thickness. In this study, we demonstrate a methylammonium (MA)-free wide bandgap perovskite for the active layer of ST-PSCs. However, achieving defect-free highly crystalline films with lower film thickness has been challenging. We report a precursor engineering approach based on an organic ammonium salt tryptamine hydro bromide (TABr) with an anion and a cation group to passivate both halide and metal ion vacancies. TABr molecules regulate the crystallization kinetics and offer highly crystalline thinner perovskite films. The champion device exhibits a power conversion efficiency (PCE) of 14.21%, along with an average visible transparency (AVT) of ∼22%. This work provides an efficient method to enhance the performance of ST-PSCs with high AVT for application in building integrated photovoltaics (BIPVs).
Perovskite solar cells (PSCs) in the pin structure are limited by nonradiative recombination at the electron transport layer (ETL) interface, which is exacerbated in narrow-bandgap (∼1.2 eV) Pb–Sn ...PSCs due to surface Sn oxidation and detrimental p-doping. Photoluminescence quantum yield studies herein indicated that ethane-1,2-diammonium (EDA) passivation only partially alleviates perovskite/ETL energetic losses. We pursued passivation of the defect-rich perovskite:ETL interface to reduce nonradiative losses; our target was to combine chemical coordination of Sn sites with the introduction of an interlayer, which we implemented by introducing long-chain carboxylic acid ligands at the perovskite surface. Treatment with oleic acid (OA) led to reduced recombination at the perovskite/ETL interface and evidence of Sn2+ coordination. This reduced the V OC deficit of Pb–Sn PSCs to 0.34 V, resulting in a 0.89 V V OC and PCE of 23.0% (22.4% stabilized). Incorporating the OA-treated Pb–Sn layer into a monolithic all-perovskite tandem, we report a 27.3% PCE (26.4% certified) and a V OC of 2.21 V.
Direct visualization of ultrafast coupling between charge carriers and lattice degrees of freedom in photo-excited semiconductors has remained a long-standing challenge and is critical for ...understanding the light-induced physical behavior of materials under extreme non-equilibrium conditions. Here, by monitoring the evolution of the wave-vector resolved ultrafast electron diffraction intensity following above-bandgap photo-excitation, we obtain a direct visual of the structural dynamics in monocrystalline 2D perovskites. Analysis reveals a surprising, light-induced ultrafast lattice ordering resulting from a strong interaction between hot-carriers and the perovskite lattice, which induces an in-plane octahedra rotation, towards a more symmetric phase. Correlated ultrafast spectroscopy performed at the same carrier density as ultrafast electron diffraction reveals that the creation of a hot and dense electron-hole plasma triggers lattice ordering at short timescales by modulating the crystal cohesive energy. Finally, we show that the interaction between the carrier gas and the lattice can be altered by tailoring the rigidity of the 2D perovskite by choosing the appropriate organic spacer layer.
A major mechanism in mid- to high-frequency acoustic propagation and reverberation in littoral environments is the scattering from rough interfaces at the boundaries of the waveguide. Although ...methods have been developed to measure the interface roughness in order to quantify the scattering, many of these methods are limited in resolution or difficult to employ over a large area. In this study, a mobile laser profiling method of measuring microbathymetry is presented. The lasers are mounted on a remotely operated vehicle (ROV) which enables large areas to be surveyed and does not require bottom mounted equipment. This system was deployed as part of the Target and Reverberation Experiment of the coast of the Florida Panhandle in May of 2013. Micorbathymetric maps and roughness spectral parameters were determined using the system.
