A Review on Reducing Grain Boundaries and Morphological Improvement of Perovskite Solar Cells from Methodology and Material‐Based Perspectives

Abstract

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smtd.201900569.Perovskite solar cells (PSCs) have achieved 25.2% of their certified efficiency and emerged as up-and-coming energy-harvesting candidates owing to their superior properties. However, perovskite films are mainly polycrystalline films, and thus, the formation of grain boundaries (GBs) is inevitable. Since GBs have numerous defect sites that provide a channel for ion migration, reducing GBs is highly significant for achieving high efficiency and long-term stability of PSCs. To this end, researchers have made efforts to produce a large crystal-based perovskite film with reduced GBs. In this study, various methods that decrease GBs and enhance the morphology of perovskites are summarized and categorized into methodology-and material-based approaches. Furthermore, a future research direction to produce high-quality and large grain-based perovskite film is also proposed.

Emerging Conductive Atomic Force Microscopy for Metal Halide Perovskite Materials and Solar Cells

“…Electronic transport behavior plays a pivotal role in device performance. [53,54] C-AFM as a high-sensitive characterization technique has been used to probe charge transport and electronic properties by measuring current under short-circuit conditions. [55][56][57][58][59][60][61][62][63][64] Generally, a large current under the same test condition indicates high conductivity of sample, which is beneficial www.advancedsciencenews.com to charge transport.…”

“…Electronic transport behavior plays a pivotal role in device performance . C‐AFM as a high‐sensitive characterization technique has been used to probe charge transport and electronic properties by measuring current under short‐circuit conditions .…”

A Facile Surface Passivation Enables Thermally Stable and Efficient Planar Perovskite Solar Cells Using a Novel IDTT‐Based Small Molecule Additive

“…[ 12 ] Therefore, various types of additives have been introduced to perovskite film to passivate GBs and surfaces, improving thermal stability of perovskite layer. [ 13 ] First, organic halide salts were introduced to perovskite films, passivating perovskite surfaces and forming a low‐dimensional perovskite which can improve thermal stability of perovskite film. [ 14–16 ] Second, organic small molecule (SM) additives also have a positive effect on both efficiency and stability of perovskite by suppressing perovskite defects.…”

Review of Interface Passivation of Perovskite Layer

“…Therefore, different metal cations, organic cations, and halogens can be used to replace the corresponding elements or ions in traditional materials [ 13 ]. In addition, HC(NH 2 ) 2 (FA) and Cs can be used to replace MA owing to their wider absorption range; consequently, a bandgap corresponding to the entire wavelength range of visible light can be achieved, thereby resulting in a higher energy conversion rate [ 14 , 15 ]. Tin-based PSCs exhibit electronic structures and semiconductor properties that are similar to those of perovskites, including a high absorption coefficient, high carrier mobility, and an ideal bandgap [ 16 , 17 , 18 ].…”

“…In addition to the development of new materials and the optimization of the preparation process, the selection of interface materials and the generation, collection, and transport efficiency of interface charges are crucial to the performance of a PSC [ 2 , 3 , 4 , 14 ]. The typically investigated flat-panel sandwich-structured PSCs are disadvantageous owing to their significant interface recombination, low carrier separation efficiency, and low stability, all of which have restricted their development.…”