Additive Engineering for Efficient and Stable Perovskite Solar Cells

Abstract

Perovskite solar cells (PSCs) have reached a certified 25.2% efficiency in 2019 due to their high absorption coefficient, high carrier mobility, long diffusion length, and tunable direct bandgap. However, due to the nature of solution processing and rapid crystal growth of perovskite thin films, a variety of defects can form as a result of the precursor compositions and processing conditions. The use of additives can affect perovskite crystallization and film formation, defect passivation in the bulk and/or at the surface, as well as influence the interface tuning of structure and energetics. Here, recent progress in additive engineering during perovskite film formation is discussed according to the following common categories: Lewis acid (e.g., metal cations, fullerene derivatives), Lewis base based on the donor type (e.g., O‐donor, S‐donor, and N‐donor), ammonium salts, low‐dimensional perovskites, and ionic liquid. Various additive‐assisted strategies for interface optimization are then summarized; additives include modifiers to improve electron‐ and hole‐transport layers as well as those to modify perovskite surface properties. Finally, an outlook is provided on research trends with respect to additive engineering in PSC development.

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

“…[22] Especially, small adjustments or inconsistencies in the preparation process can induce a strong impact on the material morphology, grain size, and crystal quality, all of which are closely related to the charge generation, extraction, and transport behavior and overall device performance. [23][24][25] Thus, it is of the great importance to unveil the origin and address these issues.…”

Gold Nanoparticles Functionalized with Fullerene Derivative as an Effective Interface Layer for Improving the Efficiency and Stability of Planar Perovskite Solar Cells

“…[ 29–35 ] In particular, fullerenes and their derivatives appeared as excellent interfacial modification layers and trap state passivators for the TiO 2 ETL, significantly enhancing the performance and stability of PSCs. [ 36–38 ] Recent studies revealed that coating the TiO 2 with a thin layer of pristine C 60 , [ 39–42 ] phenyl‐C 61 ‐butyric acid methyl ester (PCBM) [ 43–45 ] or self‐assembled monolayer (SAM) of fullerene derivatives [ 46–48 ] promotes the electron transfer and reduces the ion accumulation at the ETL/perovskite interface. Moreover, an appropriated functionalization of the fullerene derivatives with various anchoring groups can improve the crystallization of the perovskite film on the ETL and substantially eliminate the hysteresis effect of PSCs.…”

New Synthetic Route of Ultrapure Alkylammonium Iodides for Perovskite Thin Films of Superior Optoelectronic Properties

“…Similarly, other additives and impurities (acids, amines, organic halides, and water additive) can affect the colloidal chemistry occurring in the perovskite precursor solution, which in turn would have an impact on the nucleation process and perovskite thin‐film morphology. [ 10,15,16 ] As an alternative to one‐step, solution‐based processing, multiple variations of a two‐step fabrication route of metal halide perovskite films were reported. [ 17,18 ] Particularly, gas‐induced growth method, where lead iodide films are exposed to alkylamine vapor, constitutes a deposition strategy which eliminates the problem of poorly controlled purity of alkylammonium salts.…”