Directing efficient hole transport Surface defects in three-dimensional perovskites can decrease performance but can be healed with coatings based on two-dimensional (2D) perovskite such as Ruddlesden-Popper phases. However, the bulky organic groups of these 2D phases can lead to low and anisotropic charge transport. F. Zhang et al . show that a metastable polymorph of a Dion-Jacobson 2D structure based on asymmetric organic molecules reduced the energy barrier for hole transport and their transport through the layer. When used as a top layer for a triple-cation mixed-halide perovskite, a solar cell retained 90% of its initial power conversion efficiency of 24.7% after 1000 hours of operation at approximately 40°C in nitrogen. —PDS

Motivated by the rapidly rising deployment of bifacial monocrystalline‐silicon photovoltaics (PV), we investigate the durability of various PV module packaging configurations with transparent coverings on both the front and rear sides of the module. We use a series of bifacial passivated emitter and rear cell (p‐PERC) mini‐modules with systematically varying outer cover materials (glass/glass, G/G, or glass/transparent backsheet, G/TB) and encapsulant chemistries (poly [ethylene‐co‐vinyl acetate], EVA; or polyolefin, POE). We study degradation modes over 1,000 hours of combined damp heat (DH) exposure and high system voltages that can cause potential‐induced degradation (PID) under positive, zero, or negative 1,000 V cell‐to‐frame bias. We analyze the degradation modes using a combination of current–voltage measurements, impedance spectroscopy, external quantum efficiency, and spatially resolved luminescence and thermal imaging. Our results highlight various types of degradation including shunting, enhanced recombination, and series resistance increases, and we use spatially resolved characterization to separately identify the localized effects. We show that multiple PID and moisture‐ingress degradation modes severely affect EVA‐containing modules, with previously reported PID processes under negative‐bias DH and a unique observation of rear‐side surface recombination in G/EVA/G modules under positive‐bias DH. We observe significantly less degradation in POE‐containing modules, where the G/POE/G configuration exhibits minimal degradation under all stress conditions that we employ.

Spray-deposition is a low-cost, roll-to-roll compatible technique that could potentially replace spin-coating for the deposition of highly efficient perovskite solar cells. Here, perovskite active layers were fabricated in air using an ultrasonic spray system and compared with equivalent spin-coated films. A chlorine-containing perovskite ink with a wide processing window coupled with an antisolvent extraction resulted in perovskite films with relatively rougher surfaces than those spin-coated. A power conversion efficiency (PCE) of 17.3% was achieved with an average of 16.3% from 24 devices. Despite observing differences in film roughness and structure, the performance of sprayed perovskite solar cells was comparable to that of the spincoated cells processed in an inert atmosphere, showing the versatility of perovskite processing.

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