Synergetic Effect of Aluminum Oxide and Organic Halide Salts on Two‐Dimensional Perovskite Layer Formation and Stability Enhancement of Perovskite Solar Cells

Abstract

Long‐chain organic halide salts are widely used in perovskite‐based optoelectronic devices for surface passivation owing to their capability to interact with the surface defects of perovskites. Here, aluminum oxide (AlOx) is introduced via atomic layer deposition onto octylammonium iodide (OAI) to exploit the benefits of organic halide salts without generating undesired defects. The devices incorporating AlOx on OAI‐treated perovskite (OAI/AlOx) show enhancement in both device performance and photo‐stability compared to those with only treatment. A diffusion of aluminum from AlOx into the perovskite through surface characterization contributes to a uniform photo‐generated carrier transport in both the surface and the bulk of the perovskite absorber. In addition, it is revealed that light‐induced two‐dimensional perovskite formation on OAI/AlOx. This may be ascribed to preventing the loss of OA cations due to the presence of AlOx, leading to a decrease in the number of iodine anions which suppresses the light‐induced degradation of corresponding devices. Consequently, the devices show over 24% efficiency and retain their efficiency over 1000 hours under continuous light illumination.

Narrow Bandgap Metal Halide Perovskites for All-Perovskite Tandem Photovoltaics

“…Recent work shows a successful example of this, using an ultrathin noncontinuous Al 2 O 3 nanoparticle layer to improve the efficiency and stability of the mixed Sn−Pb perovskite devices . By treating the buried or exposed surface of the perovskite films, researchers in the field have widely used Al 2 O 3 and some other conventional metal oxides as thin interlayers, either with mesoporous or dense continuous form, for improving the stability and efficiency of PSCs. ,− Regarding this particular successful application of Al 2 O 3 nanoparticles in mixed Sn−Pb PSCs, the reason behind this would be the higher stability of Al 2 O 3 compared to other metal oxides, such as TiO 2 and NiO X , thanks to the stronger metal−O bond and less redox reactivity. − …”

Recent Developments in Atomic Layer Deposition of Functional Overlayers in Perovskite Solar Cells

“…In cases where passivation layers are located directly above the perovskite absorber, thickness is a crucial parameter, often limited to 1 nm or less [21,23]. In these cases, the exposure time of the perovskite material to ALD precursor gases, thermal energy, and the vacuum environment is usually confined to approximately 10 min.…”

“…These ALD-deposited barrier layers exhibit notable improvements in device stability when exposed to moisture and light. Specifically, several research groups have employed ALD to create barrier layers utilizing insulating materials such as zirconium oxide (ZrO 2 ) and aluminum oxide (Al 2 O 3 ) [21,23,34].…”

“…A recent study investigated the impact of combining perovskite surface passivation with octylammonium iodide (OAI) and ALD AlO x [21]. While the introduction of OAI on the perovskite layer yielded enhancements in device performance, it was noted that the light stability and resistance to damp heat conditions diminished when compared to unpassivated perovskite devices.…”

Unveiled effects of the methylammonium chloride additive on formamidinium lead halide: expediting carrier injection from the photoabsorber to carrier transport layers through spontaneously modulated heterointerfaces in perovskite solar cells

“…However, recent progress has successfully addressed this issue, establishing FAPbI 3 as a major photoabsorber. 5–27 Notably, the addition of alkylammonium chloride, typically methylammonium chloride (MACl), to the perovskite precursor has proven instrumental in achieving high-quality FAPbI 3 formation. 6–12 Upon heating the perovskite precursor film with the MACl additive, MACl facilitates crystal growth of FAPbI 3 and simultaneously volatilizes, contributing to improvements in film quality.…”