Two-dimensional (2D) perovskites assembled with hydrophobic bulky organic cations demonstrate much enhanced ambient stability and anisotropic carrier transport, making their devices highly promising. However, photovoltaic (PV) devices scaling up to modules using 2D perovskites lag far behind their 3D counterparts. Hence, improving the scalability and efficiency of 2D perovskite PV devices is a challenging topic. In this Perspective, from the insights of multiscale structures of 2D perovskites, we analyze the interrelated causes and propose rational solutions to these two issues. The scalability issue is scrutinized from the structures of the born inks and the ended films. The efficiency issue is investigated from the structures of the phase landscape and the lattice anharmonicity. Finally, the collective and fine moiety effect for material structure, the state-of-the-art computational methodologies, as well as the machine-learning-based diagnosis are discussed. We hope this Perspective can accelerate the roadmap for building 2D perovskite PV fab.

The production of syngas (i.e., a mixture of CO and H2) via the electrochemical reduction of CO2 and water can contribute to the green transition of various industrial sectors. Here we provide a joint academic–industrial perspective on the key technical and economical differences of the concurrent (i.e., CO and H2 are generated in the same electrolyzer cell) and separated (i.e., CO and H2 are electrogenerated in different electrolyzers) production of syngas. Using a combination of literature analysis, experimental data, and techno-economic analysis, we demonstrate that the production of synthesis gas is notably less expensive if we operate a CO2 electrolyzer in a CO-selective mode and combine it with a separate PEM electrolyzer for H2 generation. We also conclude that by the further decrease of the cost of renewable electricity and the increase of CO2 emission taxes, such prepared renewable syngas will become cost competitive.

The concept of hot carrier solar cells (HCSCs) has been proposed as a promising yet elusive path toward high-performance photovoltaics (PV), capable of surpassing the Shockley–Queisser limit by recycling energy that would otherwise be lost during thermalization. Lead halide perovskites (LHPs) have emerged as highly promising materials for PV applications. The reports of slow hot carrier (HC) cooling in these materials have ignited discussions of their potential in realizing HCSCs. Here we summarize the key findings regarding HC dynamics in LHPs, as revealed by numerous studies using advanced time-resolved spectroscopies. We also emphasize the interconnected mechanisms involved in HC cooling. In addition, we discuss the influence of nanostructuring on HC cooling dynamics in LHPs and suggest that two-dimensional LHPs, with their inherent quantum well structure, might exhibit modified phononic features and altered carrier–phonon coupling strength. We conclude by critically discussing the prospects for HCSCs, taking into account our current understanding of HC cooling and excitation conditions under sunlight.

Manipulating excitons in semiconductors has driven the evolution of today’s optoelectronic and photovoltaic devices. Engineering the dielectric constant, a key parameter that is highly associated with the Coulomb force of excitons, has recently emerged as a fresh avenue to regulate excitons from the root. Unlike three-dimensional (3D) bulk semiconductors featuring uniformly distributed dielectric constants, the dielectric constants of two-dimensional (2D) layered semiconductors exhibit spatial variability. Particularly, organic–inorganic hybrid perovskites (OIHPs) assembled with alternating organic and inorganic layers show a cyclic variation in the dielectric property, which substantially impacts exciton dynamics, including recombination and separation, offering an opportunity for the regulation of exciton-related physical attributes by dielectric engineering and the cutting-edge applications thereof. This Review documents the recent advances in the rational design of organic and inorganic constituents of 2D OIHPs for dielectric engineering. We show that dielectrically engineered OIHPs are pivotal in driving the advancements in optoelectrical and photovoltaic applications.

Metal halide perovskite quantum dots (PQDs) not only share the common feature of quantum confinement effect found in traditional quantum dots but also exhibit favorable characteristics of perovskite materials, including defect tolerance and long exciton lifetime. Thanks to these merits, within ten years of research and development, perovskite quantum dot-based solar cells (PQDSCs) have attained a certified power conversion efficiency (PCE) of 18.1%, which is, however, still far below those of the market-dominant silicon solar cells and the bulk thin-film perovskite counterparts. In this Focus Review, we analyze the state-of-the-art in the development of PQDSCs and propose innovative strategies in surface management, compositional control, and band-alignment design. The potential of utilizing PQDs’ multiple exciton generation feature is further discussed with the good hope of improving the PCE beyond the Shockley–Queisser limit.