Abstract:In this work, grain boundary (GB) potential barrier (
Δφ
GB), dopant density (Pnet), and filled trap state density (PGB,trap) were manipulated at the nanoscale by exposing the fabricated perovskite films to various relative humidity (RH) environments. Spatial mapping of surface potential in the perovskite film revealed higher positive potential at GBs than inside the grains. The average
Δφ
GB, Pnet, and PGB,trap in the perovskite films decreased from 0% RH to 25% RH exposure, but increased when the RH increas… Show more
Titanium dioxide (TiO2) has been extensively investigated in interdisciplinary research (such as catalysis, energy, environment, health, etc.) owing to its attractive physico-chemical properties, abundant nature, chemical/environmental stability, low-cost manufacturing, low toxicity, etc. Over time, TiO2-incorporated building/construction materials have been utilized for mitigating potential problems related to the environment and human health issues. However, there are challenges with regards to photocatalytic efficiency improvements, lab to industrial scaling up, and commercial product production. Several innovative approaches/strategies have been evolved towards TiO2 modification with the focus of improving its photocatalytic efficiency. Taking these aspects into consideration, research has focused on the utilization of many of these advanced TiO2 materials towards the development of construction materials such as concrete, mortar, pavements, paints, etc. This topical review focuses explicitly on capturing and highlighting research advancements in the last five years (mainly) (2014–2019) on the utilization of various modified TiO2 materials for the development of practical photocatalytic building materials (PBM). We briefly summarize the prospective applications of TiO2-based building materials (cement, mortar, concretes, paints, coating, etc.) with relevance to the removal of outdoor/indoor NOx and volatile organic compounds, self-cleaning of the surfaces, etc. As a concluding remark, we outline the challenges and make recommendations for the future outlook of further investigations and developments in this prosperous area.
Titanium dioxide (TiO2) has been extensively investigated in interdisciplinary research (such as catalysis, energy, environment, health, etc.) owing to its attractive physico-chemical properties, abundant nature, chemical/environmental stability, low-cost manufacturing, low toxicity, etc. Over time, TiO2-incorporated building/construction materials have been utilized for mitigating potential problems related to the environment and human health issues. However, there are challenges with regards to photocatalytic efficiency improvements, lab to industrial scaling up, and commercial product production. Several innovative approaches/strategies have been evolved towards TiO2 modification with the focus of improving its photocatalytic efficiency. Taking these aspects into consideration, research has focused on the utilization of many of these advanced TiO2 materials towards the development of construction materials such as concrete, mortar, pavements, paints, etc. This topical review focuses explicitly on capturing and highlighting research advancements in the last five years (mainly) (2014–2019) on the utilization of various modified TiO2 materials for the development of practical photocatalytic building materials (PBM). We briefly summarize the prospective applications of TiO2-based building materials (cement, mortar, concretes, paints, coating, etc.) with relevance to the removal of outdoor/indoor NOx and volatile organic compounds, self-cleaning of the surfaces, etc. As a concluding remark, we outline the challenges and make recommendations for the future outlook of further investigations and developments in this prosperous area.
“…For example, through the tunability of RH, PSCs give disparate J–V curves fabricated at 0%, 25%, 35%, and 45% RH ( Figure a). [ 215 ] Here, the PCE of PSCs prepared under 25% RH is the highest, which gives the smallest average GB potential barrier, dopant density, and filled trap‐state density, with values of 20.17 meV, 3.72 × 10 15 cm −3 , and 4.37 × 10 10 cm −2 , respectively, almost half of that under 0% RH. The mechanism of improved performance under humidity is attributed to the enhanced reconstruction principle [79b] .…”
Section: Design Strategies For Scsmentioning
confidence: 96%
“…Reproduced with permission. [ 215 ] Copyright 2019, Wiley‐VCH. b) SEM images of PCBM via evaporated and spun syntheses, respectively.…”
Organic/inorganic lead‐halide perovskite and its solar cells (SCs) present a new research platform for the study of special photophysical and photovoltaic (PV) characteristics across materials science, chemistry, physics, and engineering disciplines. However, the current understanding of the crystal structures, origins of figures of merit, and design strategies of SCs is inadequate. These key parameters are critical for exploring further applications of organometallic‐halide perovskite films and their SCs. Therefore, herein, the material characteristics of lead‐halide perovskite are introduced, the origins of open‐circuit voltages, short‐circuit current densities, and fill factors are explored, and three design strategies using interface engineering, bandgap engineering, and process‐control engineering for high‐quality perovskite active‐layer fabrication, outstanding efficiency, and stable SCs are summarized. Herein, process‐control engineering is introduced for the first time in perovskite SCs. Based on favorable synergistic effects, these structural features, origins of crucial parameters, and design strategies all promote the development of new schemes to explore the underlying physics, optimize functional layers and cell architectures, and improve final PV performance and device stability.
“…A large number of hydrated crystals appear between grains due to the faster diffusion of water molecules along grain boundaries. 61,65 MAPbI 3 ÁH 2 O with a wide band gap of 3.1 eV blocks the transport of carriers, causing a sharp drop in photocurrent. However, Leguy et al reported that hydration can be fully repaired after the device under dry nitrogen for several hours, and the presence of liquid water will make hydration process irreversible.…”
Section: The Influence Of Environment On the Stability Of Halide Pementioning
Finding sustainable and renewable energy to replace traditional fossil fuel is critical for reducing greenhouse gas emission and avoiding environment pollution. Solar cells that convert energy of sunlight into electricity offer a viable route for solving this issue. At present, halide perovskites are the most potential candidate materials for solar cell with considerable power conversion efficiency, whereas their stability remains a challenge. In this work, we summarize four different key factors that influence the stability of halide perovskites: (a) effect of environmental moisture on the degradation of halide perovskites. The performance of halide perovskite solar cells is reduced due to hydrated crystal hinders the diffusion of photo‐generated carriers, which can be solved by materials encapsulation technique; (b) photo‐induced instability. Through uncovering the underlying physical mechanism, we note that materials engineering or novel device structure can extend the working life of halide perovskites under continuous light exposure; (c) thermal stability. Halide perovskites are rapidly degraded into PbI2 and volatile substances as heating due to lower formation energy, whereas hybrid perovskite is little changed; (d) electric field effect in the degradation of halide perovskites. The electric field impacts significantly on the carrier separation, changes direction of photo‐induced currents and generates switchable photovoltaic effect. For each key factor, we have shown in detail the underlying physical mechanisms and discussed the strategies to overcome this stability difficulty. We expect this review from both theoretical and experimental points of view can be beneficial for development of perovskite solar cell materials and promotes practical applications.
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