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The development of vacuum‐deposited perovskite materials and devices is partially slowed down by the minor research effort in this direction, due to the high cost of the required research tools. But there is also another factor, thermal co‐deposition in high vacuum involves the simultaneous sublimation of several precursors with an overall deposition rate in the range of few Å s−1. This leads to a deposition time of hours with only a single set of process parameters per batch, hence to a long timeframe to optimize even a single perovskite composition. Here we report the combinatorial vacuum deposition of wide bandgap perovskites using 4 sources and a non‐rotating sample holder. By using small pixel substrates, more than 100 solar cells can be produced with different perovskite absorbers in a single deposition run. The materials are characterized by spatially resolved methods, including optical, morphological, and structural techniques. By fine‐tuning of the deposition rates, the gradient can be altered and the best‐performing formulations in standard depositions with rotation can be reproduced. This is viewed as an approach that can serve as a basis to prototype other compositions, overcoming the current limitations of vacuum deposition as a research tool for perovskite films. [ABSTRACT FROM AUTHOR]

Fullerene is one of the most critical materials that are widely used to improve and examine the inverted perovskite solar cells (PSCs, p‐i‐n structure). Fullerenes are known to improve the stability, lower the hysteresis, and increase the power conversion efficiency of the PSCs. Fullerene and its derivatives are often used in constructing effective PSCs. Several properties and performance of fullerenes are the key bases for testing and making effective alternatives that can improve the performance of PSCs. This review summarizes some of the most important fullerenes (i.e., fullerene and its derivatives) that are employed in inverted (p‐i‐n) PSCs and their physical properties that can overcome the well‐known shortcomings in perovskite materials. The current density–voltage hysteresis in PSC and the fullerenes role in lowering the hysteresis are discussed. Moreover, fullerenes are also reviewed as electron transport layer, cathode buffer layer, and additives for perovskites. Enhanced stability by using fullerene derivatives is illustrated. Additionally, fullerenes in flexible and tandem PSCs as well as advantages and disadvantages of fullerenes are briefly discussed. Finally, an overview of the fullerene future in PSCs is discussed with alternative nonfullerene materials used in PSC. [ABSTRACT FROM AUTHOR]

The outstanding optoelectronic properties of metal halide perovskites make them an attractive photovoltaic absorber material and has rapidly culminated in the development of highly efficient perovskite solar cells outperforming many conventional alternatives. However, the device stack still suffers from non‐negligible losses induced by various nonradiative recombination processes, which are not fully understood till date. This paper highlights recent findings attempting to understand the nature and origin of nonradiative recombination induced losses within the device stack, as well as the quantification of the magnitude and rates associated with key loss pathways mostly via steady state and transient contactless optical techniques. These studies show that nonradiative recombination processes occurring at interfaces are more dominant than those within the bulk of the perovskite absorber. However, recent findings also show that there remains room for improvement for the suppression of bulk nonradiative recombination. General routes for suppressing recombination processes within the bulk and at interfaces are discussed. Finally, current challenges are presented, which need to be overcome in order to obtain a deeper insight into the nature of defects at surfaces and within the bulk of perovskites, and ultimately enhance the power conversion efficiency of perovskite solar cells toward their thermodynamic efficiency limit. [ABSTRACT FROM AUTHOR]