Perovskite solar cells (PSCs) with an inverted structure (often referred to as the p-i-n architecture) are attractive for future commercialization owing to their easily scalable fabrication, reliable ...operation and compatibility with a wide range of perovskite-based tandem device architectures
. However, the power conversion efficiency (PCE) of p-i-n PSCs falls behind that of n-i-p (or normal) structure counterparts
. This large performance gap could undermine efforts to adopt p-i-n architectures, despite their other advantages. Given the remarkable advances in perovskite bulk materials optimization over the past decade, interface engineering has become the most important strategy to push PSC performance to its limit
. Here we report a reactive surface engineering approach based on a simple post-growth treatment of 3-(aminomethyl)pyridine (3-APy) on top of a perovskite thin film. First, the 3-APy molecule selectively reacts with surface formamidinium ions, reducing perovskite surface roughness and surface potential fluctuations associated with surface steps and terraces. Second, the reaction product on the perovskite surface decreases the formation energy of charged iodine vacancies, leading to effective n-type doping with a reduced work function in the surface region. With this reactive surface engineering, the resulting p-i-n PSCs obtained a PCE of over 25 per cent, along with retaining 87 per cent of the initial PCE after over 2,400 hours of 1-sun operation at about 55 degrees Celsius in air.
The double perovskite Cs2AgBiBr6 single crystal holds great potential for detecting applications because of its low minimum detectable dose rate and toxic‐free merit. Nevertheless, the disordered ...arrangement of Ag+/Bi3+ usually gives rise to unexpected structural distortion and thereafter heavily influences the photoelectric properties of the Cs2AgBiBr6 single crystal. Herein, phenylethylamine bromide is demonstrated to be capable of in situ regulation of the order–disorder phase transition in the Cs2AgBiBr6 single crystal. The improved ordering extent of alternatively arranged AgX65− and BiX63− octahedra is theoretically and experimentally proven to decrease the defect density and suppress self‐trapped exciton formation, and thereby tune the band gap and enhance the carrier mobility, which consequently promotes its application in an X‐ray detector. The performance of a corresponding detector based on PEA‐Cs2AgBiBr6 single crystal displays superior performances, e.g., longer carrier drift distance, higher photoconductive gain, and faster current response (13 vs 3190 µs). Prominently, the as‐fabricated PEA‐Cs2AgBiBr6 single‐crystal X‐ray detector has an extremely high sensitivity with a value of 288.8 µC Gyair−1 cm−2 under a bias of 50 V (22.7 V mm−1), which largely outperforms those of their counterparts with lower ordering structure.
Phenylethylamine bromide is demonstrated to be capable of improving the ordering extent of alternatively arranged AgX65− and BiX63− octahedra in a Cs2AgBiBr6 single crystal, and thereby tuning the band gap and suppressing self‐trapped exciton formation, which consequently promotes its application in an X‐ray detector with faster current response and higher sensitivity, which largely outperforms the devices based on lower‐ordering single crystals.
This paper addresses the issue of minimizing support material in additive manufacturing (AM) during topology optimization (TO) in order to reduce material and post-processing costs. The TO method ...developed in this paper utilizes the moving morphable components (MMC) approach, where a structure is composed of several building blocks. This work introduces minimum build angle constraints to eliminate overhanging edges, supplementing these with penalty functions to ensure connectivity between building blocks, such that the TO output is printable. The MMC approach uses explicit geometric entities for the morphable components that are controlled by geometric parameters, such as length, thickness, and angle. These parameters are the design variables. Using this approach enables the formulation of geometric manufacturing constraints and the construction of CAD models, which are important advantages of the MMC method. Examples of a short cantilever beam and an MBB beam demonstrate the capabilities of the TO methods.
Lead halide perovskite (ABX3) has attracted considerable attention due to its applicability as absorber layers in highly efficient photovoltaic cells. With regard to the lead toxicity, ...double‐metallic lead‐free perovskite, A2BIBIIIX6, in which the neighboring B+ and B3+ sites in the crystal microstructure are alternately occupied by monovalent‐metal and trivalent‐metal cations, is regarded to be a promising alternative to the widely used lead‐based perovskites. This review aims to summarize the recent advances in the new class of A2BIBIIIX6 double‐metallic lead‐free perovskites. In particular, the electronic structure, synthesis, property, and their applications in devices, for example, photovoltaics, photodetectors, and light emitting diodes, is carefully classified and presented. Notably, the theoretical calculations point out that there is much room toward potential applications for this new class of perovskite materials. The present review provides a holonomic conclusion and opens new perspectives toward realizing higher performance of A2BIBIIIX6‐based devices.
The recent progress in double‐metallic lead‐free perovskite materials and devices is comprehensively reviewed. In particular, theory calculation, electronic structure, and fundamental properties of double perovskites are deliberated. The achievements and challenges in their application including solar cells, photon detectors, and laser devices, are summarized. In addition, the viewpoints for future research of this class of perovskites are also provided.
•Enhancing deposited silver layer adhesion via designing filler incorporating matrix.•Fillers with different functional conditions, sizes or dimensions were compared.•Adhesion depended on surface ...roughness and mechanical property of fillers.
A new “bottom up” strategy via incorporating specific fillers into polymeric matrix and forming rough surface as well as exposed fillers without further surface treatment is presented to replace conventional palladium (Pd) activation or molecular grafting in polymer surface metallization hopefully. Transmission electron microscope (TEM), 3D profile, cross-cut testing and surface enhanced Raman spectroscopy (SERS) were conducted to studied the the effects of fillers in generating rough surface and improving adhesion. The results showed that, 1D/ 2D, functionalized fillers generated rougher surface, adhesion improved significantly after functionalization. Before functionalization, the adhesion is influenced by surface roughness and original functional groups of the fillers and after functionalizaton, the adhesion is depended by the mechanical properties and behaviors of the fillers.
•DND enhanced the TC of MWCNT-KH nanocomposite but hardly in p-MWCNT nanocomposite.•Peak shifts of hydrogen bonds were found in DND and MWCNT-KH hybrids.•The hydrogen bonds led the DND attach the ...MWCNT-KH to improve the dispersion.•Using hydrogen bonds to control internal structure of hybrid fillers is promising.
The lack of thermal conductance (TC) remains to be a challenge for epoxy resin. Fortunately, the thermal conductance of epoxy resin can be effectively improved by filler incorporation. Recently, compositing epoxy resin with hybrid filler system has been the direction for the development of next-generation thermal conductive functional materials. In this paper, epoxy-based nanocomposites containing nanodiamonds (DNDs)/pristine multi-walled carbon nanotubes (p-MWCNTs) and DNDs/KH550 functionalized MWCNTs (MWCNTs-KH) as the hybrid filler system were prepared respectively, and the thermal conductance of the nanocomposites was compared. The addition of DNDs was found to play a dominating role in the MWCNTs-KH filler systems (0.2 g, from 0.30 W/mK to 0.34 W/mK), but hardly has any effect on the p-MWCNTs filler system (0.2 g, from 0.24 to 0.26 W/mK only). Furthermore, the TC of the DNDs/MWCNTs-KH (2 g) epoxy-based nanocomposite increased to 0.45 W/mK, displaying an enhancement of 114.2 %. A shift of 5 cm-1 recorded by FTIR and the shift of CO revealed by XPS for DNDs/MWCNTs-KH strongly confirmed the existence of hydrogen bonds. Associating with the characterization results of SEM, TEM and dispersion qualitative experiment, the significant improvement in the TC of DNDs/MWCNTs-KH (2 g) epoxy-based nanocomposite was attributed to the hydrogen bond attachment between DNDs and MWCNTs-KH. The mechanism is that the attachment improves the dispersion of the fillers in epoxy, leading to the formation of a more effective thermal conductive network, thus, the enhanced TC. This work may inspire future studies in hybrid filler recognition and self-assemble technology via hydrogen bonds.
The spin–orbit coupling (SOC) effect of lead (Pb) atoms is a consequential attribute of the unique optoelectronic and defect properties of lead halide perovskites (LHPs). It has been found that the ...SOC effect varies significantly as the structural dimensionality changes with an anomalous dependence; i.e., while the SOC strength monotonically decreases as structural dimensionality decreases from three-dimensional (3D) to two-dimensional (2D) and then to one-dimensional (1D), the zero-dimensional (0D) SOC strength is greater than the 1D SOC strength. The underlying mechanism of such a SOC dimensionality dependence anomaly remains elusive. In this work, we show that Pb 6p energy splitting increases from 3D to 2D and to 1D LHPs due to the increased degree of distortion, leading to a reduced SOC strength. However, the degree of distortion decreases for the 1D to 0D transformation, resulting in reverse SOC enhancement. The mechanism described in this work can be employed to regulate the SOC effect in the design of perovskite materials.
Recently, the interfacial bonding between nanodiamonds (DNDs) and multi‐walled carbon nanotubes (MWCNTs) in epoxy‐based nanocomposites were found. In this work, effects of amino functionalization on ...MWCNTs and DNDs introduction on rheology, dynamic mechanical properties, and thermal stability of MWCNTs epoxy‐based nanocomposites are discussed. The results show that pristine MWCNTs increase the complex viscosity, lower the molecular weight of epoxy net chains as well as glass transition temperature (Tg), and expand the phase separation. Amino functionalization of MWCNTs make the behaviors above disappeared nearly. Besides, introduction DNDs improved Tg and restricted the phase separation as well, but the high complex viscosity and non‐Newtonian behavior remains. This work may provide inspirations for the further researches about hybrid fillers.
Interface between nanodiamonds (DNDs) and multi‐walled carbon nanotubes (MWCNTs) were essential for epoxy‐based nanocomposites. In this work, the rheological behaviors, dynamic mechanical properties, and thermal stability were investigated. It was found that the embedding of pristine MWCNTs increase the complex viscosity, lower the molecular weight of epoxy net chains and glass transition temperature via expanding the phase separation. Amino functionalization of MWCNTs and extra introduction of DNDs could restricted the phase separation but the high viscosity remains effectively.
.
Abstract
The double perovskite Cs
2
AgBiBr
6
single crystal holds great potential for detecting applications because of its low minimum detectable dose rate and toxic‐free merit. Nevertheless, the ...disordered arrangement of Ag
+
/Bi
3+
usually gives rise to unexpected structural distortion and thereafter heavily influences the photoelectric properties of the Cs
2
AgBiBr
6
single crystal. Herein, phenylethylamine bromide is demonstrated to be capable of in situ regulation of the order–disorder phase transition in the Cs
2
AgBiBr
6
single crystal. The improved ordering extent of alternatively arranged AgX
6
5−
and BiX
6
3−
octahedra is theoretically and experimentally proven to decrease the defect density and suppress self‐trapped exciton formation, and thereby tune the band gap and enhance the carrier mobility, which consequently promotes its application in an X‐ray detector. The performance of a corresponding detector based on PEA‐Cs
2
AgBiBr
6
single crystal displays superior performances, e.g., longer carrier drift distance, higher photoconductive gain, and faster current response (13 vs 3190 µs). Prominently, the as‐fabricated PEA‐Cs
2
AgBiBr
6
single‐crystal X‐ray detector has an extremely high sensitivity with a value of 288.8 µC Gy
air
−1
cm
−2
under a bias of 50 V (22.7 V mm
−1
), which largely outperforms those of their counterparts with lower ordering structure.
Inorganic CsPbIxBr3−x perovskite solar cells (PSCs) have gained enormous interest due to their excellent thermal stabilities. However, their intrinsically poor moisture stability hampers their ...further development. Herein, a chromium‐based metal–organic framework group is intercalated inside the inorganic PbI framework, resulting in a new multiple‐dimensional electronically coupled CsPbI2Br perovskite. In this structurally and electronically coupled perovskite, the π‐conjugated terpyridyl can delocalize the excited valence electrons of metal Cr3+ ion, enabling multi‐interactive charge‐carrier transport channels within CsPbI2Br perovskites. The stability and efficiency of the produced devices are substantially enhanced in comparison to their counterparts with only a pristine CsPbI2Br active layer. The optimized all‐inorganic PSC yields a power conversion efficiency (PCE) as high as 17.02%. Remarkably, the stabilized device retains 80% of its PCE after 1000 h in the ambient atmosphere. This study provides a new paradigm toward addressing the stability challenge of the inorganic perovskite while enhancing its carrier transport ability.
Incorporation of the chromium‐based metal–organic framework as an A‐site cation allows realizing a new multiple‐dimensional electronically coupled CsPbI2Br perovskite, which is theoretically and experimentally proved to improve the carrier transport ability and stability of perovskite solar cells (PSCs). Consequently, the as‐fabricated CsPbI2Br PSCs demonstrate 17.02% power conversion efficiency while superior long‐term stability.
