Doping and alloying for improved perovskite solar cells Zhou, Yuanyuan; Zhou, Zhongmin; Chen, Min ...
Journal of materials chemistry. A, Materials for energy and sustainability,
01/2016, Volume:
4, Issue:
45
Journal Article
Peer reviewed
Doping and/or alloying in the various layers in perovskite solar cells (PSCs) is playing a key role in the success of this new photovoltaic (PV) technology. Here we present a brief review of doping ...and alloying approaches used to enhance the efficacy of the hybrid organic-inorganic perovskite (HOIP) layer, the electron-transporting layer (ETL), the hole-transporting layer (HTL), and the electrode layers in PSCs. While the effectiveness of these approaches is beyond doubt, the fundamental understanding of doping and alloying in the majority of the cases is lacking. This presents vast research opportunities in elucidating the roles of doping and alloying, and the rational design and implementation of these approaches for enhanced PSCs performance.
Studies on doping and alloying for the advancement of perovskite solar cells are critically reviewed.
Significant effort is being devoted to the search for all-inorganic Pb-free halide perovskites (HPs) for photovoltaic applications. However, candidate HPs that combine all the desirable attributes — ...ease of synthesis, favorable bandgaps, outstanding optoelectronic properties, high stability, no toxicity — are extremely rare. Here, we demonstrate experimentally the promise of cesium titanium(IV) bromide (Cs2TiBr6), a part of the Ti-based vacancy-ordered double-perovskite halides family, in perovskite solar cells (PSCs). We show, for the first time, that high-quality Cs2TiBr6 thin films can be prepared through a facile low-temperature vapor-based method. These films exhibit a favorable bandgap of ∼1.8 eV, long and balanced carrier-diffusion lengths exceeding 100 nm, suitable energy levels, and superior intrinsic and environmental stability. The first demonstration of Cs2TiBr6 thin films-based PSCs shows stable efficiency of up to 3.3%. Insights into the Cs2TiBr6 film-formation mechanisms and the PSC device operation are provided, pointing to directions for improving Ti-based PSCs.
Display omitted
•Fabrication of Cs2TiBr6 halide perovskite thin films is demonstrated for the first time•Cs2TiBr6 thin films have ∼1.8 eV bandgap and balanced carrier-diffusion lengths >100 nm•Cs2TiBr6 thin films are highly stable under environmental (humidity/heat/light) stresses•First ever solar cells using Cs2TiBr6 thin films show a stable efficiency of up to 3.3
Halide perovskites (HPs) have attracted a great deal of attention in the field of photovoltaics (PVs) in recent years. The efficiency of perovskite solar cells (PSCs) has seen an unprecedentedly rapid rise within a short period of time. However, the toxicity of Pb and the volatility of the organic ions in the state-of-the-art HP light absorbers have been recognized as the two major obstacles in the path of PSC development and commercialization. Thus, the search is on for all-inorganic, Pb-free HPs for use in PSCs. In this study, we demonstrate experimentally the promise of a new candidate HP: cesium titanium(IV) bromide, a member of a larger family of Ti-based HPs that are all-inorganic, non-toxic, and contain only earth-abundant elements. The exploration of PSCs based on this new family of HPs is likely to have a lasting impact on the global landscape of environmentally friendly PVs, and these materials may also find use in other promising (opto)electronic applications.
Cesium titanium(IV) halide perovskites (HPs) are promising all-inorganic, Pb-free materials for perovskite solar cells (PSCs). Here we show that high-quality, uniform thin films of Cs2TiBr6 HP can be prepared through a facile low-temperature vapor-based method. These thin films exhibit a favorable bandgap of ∼1.8 eV, long and balanced carrier-diffusion lengths >100 nm, suitable energy levels, and superior intrinsic and environmental stability. The first planar-heterojunction PSCs based on Cs2TiBr6 thin films show a stable efficiency of up to 3.3%.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Methylammonium‐mediated phase‐evolution behavior of FA1−xMAxPbI3 mixed‐organic‐cation perovskite (MOCP) is studied. It is found that by simply enriching the MOCP precursor solutions with excess ...methylammonium cations, the MOCPs form via a dynamic composition‐tuning process that is key to obtaining MOCP thin films with superior properties. This simple chemical approach addresses several key challenges, such as control over phase purity, uniformity, grain size, composition, etc., associated with the solution‐growth of MOCP thin films with targeted compositions.
Under control: FA1−xMAxPbI3 mixed‐organic‐cation iodide perovskite (MOCP) thin films have been synthesized. By simply enriching the precursor solutions with methylammonium cations, the MOCPs form via a dynamic composition‐tuning process that is key to obtaining thin films with superior properties, exact composition, excellent uniformity, and extra‐large grains.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The alloying behavior between FAPbI3 and CsSnI3 perovskites is studied carefully for the first time, which has led to the realization of single‐phase hybrid perovskites of (FAPbI3)1−x(CsSnI3)x ...(0<x<1) compositions with anomalous bandgaps. (FAPbI3)1−x(CsSnI3)x perovskites exhibit stable, homogenous composition/microstructure at the nanoscale, as confirmed by microscopic characterization. The ideal bandgap of 1.3 eV for single‐junction solar cell operation is achieved in the rationally‐tailored (FAPbI3)0.7(CsSnI3)0.3‐composition perovskite. Solar cells based on this new perovskite show power conversion efficiency up to 14.6 %.
Thin‐film photovoltaics: Significant progress has been made on the formation of mixed cation‐stablized Pb–Sn alloy perovskite materials made from FAPbI3 and CsSnI3 halide perovskites (FA=formamidinium). Solar cells based on an alloy in this system with an ideal bandgap show power conversion efficiencies up to 14.6 %.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The lack of river sand is becoming increasingly serious. In this study, we consider how to use sea sand to prepare innovative construction and building materials with excellent mechanical and ...durability properties. Sulphate corrosion causes expansion, cracking and spalling of concrete, resulting in the reduction or even loss of concrete strength and cementation force. In this paper, artificial seawater, sea sand, industrial waste, steel fiber and polycarboxylate superplasticizer were used to prepare ultra-high-performance polymer cement mortar (SSUHPC), and the sulphate corrosion mechanism was investigated. The strength and cementation force of mortar on the SSUHPC surface decreased and flaked off with the development of sulphate erosion, and the steel fiber rusted and fell off. A 3D model was established based on X-ray computed tomography (X-CT), and the results showed that SSUHPC maintained excellent internal structural characteristics despite severe sulphate erosion on the surface. Mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were adopted to investigate the sulphate corrosion mechanism of SSUHPC. We found a transition zone within 1-5 mm of the surface of SSUHPC. The Vickers hardness of mortar in this area was increased by 5~15%, and the porosity was reduced to 3.8489%. Obvious structural damage did not occur in this area, but a high content of gypsum appeared. UHPC prepared with seawater sea sand was found to have better sulphate resistance than that prepared with freshwater river sand, which supports the development and utilization of sea sand in concrete.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
In order to obtain the unique properties of graphene-based composites, to realize homogeneous dispersion of graphene throughout the polymer matrix remains the key challenge. In this work, ...edge-oxidized graphene/polypropylene (EOGr/PP) composites with well-dispersed EOGr in PP matrix, synchronously exhibiting high electrical conductivity and thermal property, were simply fabricated for the first time using a novel strategy by in situ artificial PP latex preparation in the presence of EOGr based on solution-emulsification technique. The good dispersion state of EOGr in the PP matrix was demonstrated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). A blue shift in Raman G peak of the EOGr nanosheets was observed in the EOGr/PP composites, indicating the strong interactions between the EOGr nanosheets and the PP matrix. The onset crystallization and crystallization peak temperatures increased as the EOGr loading increases due to its good nucleating ability. An improved thermal stability of EOGr/PP composites was observed as evaluated by TGA. The EOGr/PP composites showed an insulator-to-conductor percolation transition in between that of 1 and 2 wt% EOGr content. Such strategy provides a very effective pathway to fabricate high-performance nonpolar polymer/graphene composites with excellent dispersion state of graphene.
The stability of formamidinium lead iodide (FAPbI3) perovskites is generally improved by incorporating cesium (Cs) into the crystal structure. However, the effectiveness of this approach is limited ...by the intrinsically low solid-solubility of Cs in bulk FAPbI3. To circumvent this issue, we demonstrate a method that entails solution-deposition of high-Cs-content Cs1–x FA x PbI3 alloy quantum dots (QDs) onto a bulk Cs-lean FAPbI3-based thin film. This results in a thin film with a Cs-rich QD surface layer, which stabilizes the thin film against the ambient environment. Stable, efficient perovskite solar cells based on these new thin-film structures are demonstrated.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
The effects of magnesium maleate (MgMA) and maleic anhydride (MAH) on the interfacial interaction and the shape memory properties of ethylene propylene diene monomer (EPDM) and polypropylene (PP) ...thermoplastic vulcanizate (TPV) with sea island structure prepared by dynamic vulcanization were investigated in this study. PP matrix could maintain the temporary shape of TPVs and the crosslinked EPDM phase supplied stress to drive the deformed shape recovery during the shape memory process. MgMA and MAH grafted on PP and EPDM chains verified by FTIR, DMA and SEM, which improved the interfacial compatibility of EPDM and PP and enhanced the efficiency of stress transfer in the shape memory process. The shape fixity ratio (Rf) and shape recovery ratio (Rr) of TPVs compatibilized by MgMA and MAH were almost above 80%. The shape memory property and the mechanical performance of TPVs were all improved compared to that of the sample without compatibilization.
Display omitted
•We produced an ethylene propylene diene monomer and polypropylene thermoplastic vulcanizate by dynamic vulcanization.•The TPV was compatibilized by magnesium maleate (MgMA) and maleic anhydride (MAH) with good shape memory performance.•The shape fixity ratio (Rf) and shape recovery ratio (Rr) of compatibilized TPVs were almost above 80%.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A post-photochemical cross-linking strategy was successfully demonstrated to enhance the stability of polyelectrolyte poly（allylamine hydrochloride）（PAH）/poly（vinylsulfonic acid sodium salt）（PVS） ...multilayers. Con- ventional polyelectrolyte multilayers of PAH/PVS are usually fabricated through electrostatic layer-by-layer（LbL） assembly, resulting in poor stability, especially in basic solutions, which leads to the urgent demand for converting weak electrostatic interactions into covalent bonds to enhance the stability of the multilayers. This stability problem has been ultimately addressed by post-infiltrating a photosensitive cross-linking agent, 4,4＇-diazostilbene-2,2＇- disulfonie acid disodium salt（DAS）, into the LbL assembled films to initiate the photochemical reaction to cross-link the multilayers. The obviously improved stability of the photo-cross-linked multilayers was demonstrated through experiments with basic solution treatments. Compared to the complete decomposition of uncross-linked multilayers in basic solution, over 74.4% of the covalently cross-linked multilayers were retained under the same conditions, even after a longer duration of basic solution treatment.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
State‐of‐the‐art perovskite solar cells (PSCs) have bandgaps that are invariably larger than 1.45 eV, which limits their theoretically attainable power conversion efficiency. The emergent mixed‐(Pb, ...Sn) perovskites with bandgaps of 1.2–1.3 eV are ideal for single‐junction solar cells according to the Shockley–Queisser limit, and they have the potential to deliver higher efficiency. Nevertheless, the high chemical activity of Sn(II) in these perovskites makes it extremely challenging to control their physical properties and chemical stability, thereby leading to PSCs with relatively low PCE and stability. In this work, the authors employ the Lewis‐adduct SnF2·3FACl additive in the solution‐processing of ideal‐bandgap halide perovskites (IBHPs), and prepare uniform large‐grain perovskite thin films containing continuously functionalized grain boundaries with the stable SnF2 phase. Such Sn(II)‐rich grain‐boundary networks significantly enhance the physical properties and chemical stability of the IBHP thin films. Based on this approach, PSCs with an ideal bandgap of 1.3 eV are fabricated with a promising efficiency of 15.8%, as well as enhanced stability. The concept of Lewis‐adduct‐mediated grain‐boundary functionalization in IBHPs presented here points to a new chemical route for approaching the Shockley–Queisser limit in future stable PSCs.
A novel concept of Lewis‐adduct mediated grain‐boundary functionalization is demonstrated for the fabrication of mixed‐(Pb, Sn) ideal‐bandgap perovskite solar cells with high efficiency and superior stability. The as‐formed continuous Sn(II)‐rich grain boundaries not only annihilate the Sn vacancies in mixed‐(Pb, Sn) perovskites, but also serve as nanoscale encapsulation layers that protect the grains from degradation under environmental stresses.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
PDF
