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2024 Volume 43 Issue 6
2024, 43(6): 100212
doi: 10.1016/j.cjsc.2024.100212
Abstract:
Materials exhibiting dielectric switching response and photoluminescence (PL) are promising for sensors and information storage. In previous research, we synthesized a series of materials with red or green PL and dielectric switching capabilities by incorporating luminescent metal halides into organic ammonium compounds. However, effective modification to synthesize organic-inorganic hybrid materials with dielectric switching response and orange PL continues to be a challenge in the respective fields. Orange PL materials are valuable for switching and sensors, and most orange light sources are derived from rare earth elements, making them harder to obtain. We have successfully synthesized two organic-inorganic hybrid materials ([CMPD]PbBr3 (1) and [BMPD]PbBr3 (2), CMPD = N-ClCH2-N-methylpiperidine, BMPD = N-BrCH2-N-methylpiperidine) that exhibit both orange PL and dielectric switching response. When Cl in compound 1 is substituted by Br in compound 2, the phase transition temperature of the compound is elevated by 45 K. These compounds exhibit captivating orange light emission when exposed to ultraviolet lamps. This research provides insights into exploring multifunctional materials with orange PL and dielectric switching response and provides proof for halogen substitution strategies to design materials with higher phase transition temperatures.
Materials exhibiting dielectric switching response and photoluminescence (PL) are promising for sensors and information storage. In previous research, we synthesized a series of materials with red or green PL and dielectric switching capabilities by incorporating luminescent metal halides into organic ammonium compounds. However, effective modification to synthesize organic-inorganic hybrid materials with dielectric switching response and orange PL continues to be a challenge in the respective fields. Orange PL materials are valuable for switching and sensors, and most orange light sources are derived from rare earth elements, making them harder to obtain. We have successfully synthesized two organic-inorganic hybrid materials ([CMPD]PbBr3 (1) and [BMPD]PbBr3 (2), CMPD = N-ClCH2-N-methylpiperidine, BMPD = N-BrCH2-N-methylpiperidine) that exhibit both orange PL and dielectric switching response. When Cl in compound 1 is substituted by Br in compound 2, the phase transition temperature of the compound is elevated by 45 K. These compounds exhibit captivating orange light emission when exposed to ultraviolet lamps. This research provides insights into exploring multifunctional materials with orange PL and dielectric switching response and provides proof for halogen substitution strategies to design materials with higher phase transition temperatures.
2024, 43(6): 100256
doi: 10.1016/j.cjsc.2024.100256
Abstract:
Metal halide perovskites have made significant progress in X-ray detection owing to their exceptional optoelectronic properties. However, most of these materials suffer from toxic element lead and require for high operating voltages. Hence, it is imperative to explore environmentally friendly perovskite crystals without external bias for X-ray detection. Herein, we strategically introduce chiral cations to synthesize a pair of lead-free chiral-polar hybrid perovskites (S-MPz)6Bi3I21·6H2O and (R-MPz)6Bi3I21·6H2O (1S and 1R, S/R-MPz = S/R-2-methylpiperazinium), which exhibit strong circular dichroism (CD) signals with an anisotropic g-factor reaching approximately 0.017. Significantly, the chiral-polar feature gives rise to distinctive spontaneous polarization, which leads to a photovoltage of 1.1 V under X-ray illumination, endowing self-powered detection capabilities for X-ray. Further exploration of X-ray devices based on 1R single crystal (SC) demonstrates a high sensitivity of 5.2 μC Gyair−1 cm−2 at zero bias. This study realizes passive X-ray detection depending on the intrinsic spontaneous polarization induced built-in electric field of chiral-polar perovskite, providing an effective approach to the chemical design of desired materials for high-performance “green” self-powered radiation detection.
Metal halide perovskites have made significant progress in X-ray detection owing to their exceptional optoelectronic properties. However, most of these materials suffer from toxic element lead and require for high operating voltages. Hence, it is imperative to explore environmentally friendly perovskite crystals without external bias for X-ray detection. Herein, we strategically introduce chiral cations to synthesize a pair of lead-free chiral-polar hybrid perovskites (S-MPz)6Bi3I21·6H2O and (R-MPz)6Bi3I21·6H2O (1S and 1R, S/R-MPz = S/R-2-methylpiperazinium), which exhibit strong circular dichroism (CD) signals with an anisotropic g-factor reaching approximately 0.017. Significantly, the chiral-polar feature gives rise to distinctive spontaneous polarization, which leads to a photovoltage of 1.1 V under X-ray illumination, endowing self-powered detection capabilities for X-ray. Further exploration of X-ray devices based on 1R single crystal (SC) demonstrates a high sensitivity of 5.2 μC Gyair−1 cm−2 at zero bias. This study realizes passive X-ray detection depending on the intrinsic spontaneous polarization induced built-in electric field of chiral-polar perovskite, providing an effective approach to the chemical design of desired materials for high-performance “green” self-powered radiation detection.
2024, 43(6): 100257
doi: 10.1016/j.cjsc.2024.100257
Abstract:
In the realm of molecular phase transition research, particularly for applications in sensors, data storage and switching technologies, the role of organic-inorganic hybrid perovskite materials has been increasingly recognized for their significant potential. Nevertheless, hybrid post-perovskites, as a critical subclass of perovskites, have not been thoroughly studied and mainly limit in the instances based on polyatomic bridging agents like dicyanamide (dca−) and non-cyclic organic cations. Herein, a polar cyclic quaternary ammonium cation, N,N-dimethylpyrrolidinium (DMP+), was used to assemble a new hybrid post-perovskite, (DMP)[Mn(dca)3] (1), which undergoes a phase transition from orthorhombic Bmmb to monoclinic P21/n space group at 249 K. By employing multiple techniques such as differential scanning calorimetry, variable-temperature single-crystal X-ray analysis, dielectric measurements, and Hirshfeld surface analysis, we disclosed the role of polar cyclic quaternary ammonium DMP+ in elevating the phase-transition temperature by 48 K, generating significant dielectric switching effect and facilitating interlayer sliding of inorganic framework.
In the realm of molecular phase transition research, particularly for applications in sensors, data storage and switching technologies, the role of organic-inorganic hybrid perovskite materials has been increasingly recognized for their significant potential. Nevertheless, hybrid post-perovskites, as a critical subclass of perovskites, have not been thoroughly studied and mainly limit in the instances based on polyatomic bridging agents like dicyanamide (dca−) and non-cyclic organic cations. Herein, a polar cyclic quaternary ammonium cation, N,N-dimethylpyrrolidinium (DMP+), was used to assemble a new hybrid post-perovskite, (DMP)[Mn(dca)3] (1), which undergoes a phase transition from orthorhombic Bmmb to monoclinic P21/n space group at 249 K. By employing multiple techniques such as differential scanning calorimetry, variable-temperature single-crystal X-ray analysis, dielectric measurements, and Hirshfeld surface analysis, we disclosed the role of polar cyclic quaternary ammonium DMP+ in elevating the phase-transition temperature by 48 K, generating significant dielectric switching effect and facilitating interlayer sliding of inorganic framework.
2024, 43(6): 100270
doi: 10.1016/j.cjsc.2024.100270
Abstract:
In summary, Jiang et al. have successfully developed a rational anchoring strategy to firstly investigate molecular horizontal dipole ratio for solution processable AIE-TADF emitters. This work not only reports the unprecedented EQE in non-doped solution processable OLEDs and MR OLEDs, but also firstly sheds new light on molecular horizontal orientation for solution-processed TADF emitters. What deserves to be further mentioned is that the peripheral functional group promotes the realization of molecular orientation from isotropic to horizontal, providing a new strategy for easy access to high-performance solution processable organic emitters.
In summary, Jiang et al. have successfully developed a rational anchoring strategy to firstly investigate molecular horizontal dipole ratio for solution processable AIE-TADF emitters. This work not only reports the unprecedented EQE in non-doped solution processable OLEDs and MR OLEDs, but also firstly sheds new light on molecular horizontal orientation for solution-processed TADF emitters. What deserves to be further mentioned is that the peripheral functional group promotes the realization of molecular orientation from isotropic to horizontal, providing a new strategy for easy access to high-performance solution processable organic emitters.
2024, 43(6): 100272
doi: 10.1016/j.cjsc.2024.100272
Abstract:
Two-dimensional (2D) lead halide perovskites have attracted tremendous attention due to their outstanding physical properties. However, the presence of toxic lead is a major problem for large-scale applications. Here, we report the synthesis, phase transition, dielectric and photoluminescence (PL) properties of a lead-free 2D Ge-based perovskite (BIM)2GeI4 (BIM = benzimidazolium) which experiences a phase transition at 405 K accompanied by an order-disorder change of organic spacer. Moreover, the step-like dielectric transition near the phase transition temperature makes it suitable for dielectric switching. Meanwhile, (BIM)2GeI4 has a direct bandgap of 2.23 eV and broadband emission from 550 to 1000 nm, implying its unique optical property for potential near-infrared lighting and displaying. This work provides a fresh example for the development of lead-free 2D Ge-based perovskite with potential applications in the fields of optoelectronics and high temperature dielectric switching.
Two-dimensional (2D) lead halide perovskites have attracted tremendous attention due to their outstanding physical properties. However, the presence of toxic lead is a major problem for large-scale applications. Here, we report the synthesis, phase transition, dielectric and photoluminescence (PL) properties of a lead-free 2D Ge-based perovskite (BIM)2GeI4 (BIM = benzimidazolium) which experiences a phase transition at 405 K accompanied by an order-disorder change of organic spacer. Moreover, the step-like dielectric transition near the phase transition temperature makes it suitable for dielectric switching. Meanwhile, (BIM)2GeI4 has a direct bandgap of 2.23 eV and broadband emission from 550 to 1000 nm, implying its unique optical property for potential near-infrared lighting and displaying. This work provides a fresh example for the development of lead-free 2D Ge-based perovskite with potential applications in the fields of optoelectronics and high temperature dielectric switching.
2024, 43(6): 100277
doi: 10.1016/j.cjsc.2023.100277
Abstract:
In summary, this study reported the synthesis of two naphthalene imide small molecules, namely NDT-1 and NDT-2, which were successfully used as ETMs in OSCs. The introduction of ester functional groups at the π-bridge units in NDT-2 resulted in (1) an enlarged molecular dihedral angle, improved alcohol solubility, enhanced film conductivity and film-forming quality; (2) suppression of charge recombination, enhancement of electron mobility and reduction of series resistance, leading to a significant increase in JSC; (3) almost no effect on VOC and FF. Ultimately, OSC devices based on PM6:BTP-eC9 with NDT-2 as the ETM achieved a remarkable PCE of 17.1% (a VOC of 0.839 V, a JSC of 28.2 mA cm-2 and FF of 72.1%), demonstrating superior photovoltaic performance compared to NDT-1 (PCE = 13.2%). This work discovered that the ester-modified NI molecules exhibit excellent alcohol solubility and film-forming ability, providing valuable insights for the development of NI molecules as efficient ETMs used in high-efficient OSCs
In summary, this study reported the synthesis of two naphthalene imide small molecules, namely NDT-1 and NDT-2, which were successfully used as ETMs in OSCs. The introduction of ester functional groups at the π-bridge units in NDT-2 resulted in (1) an enlarged molecular dihedral angle, improved alcohol solubility, enhanced film conductivity and film-forming quality; (2) suppression of charge recombination, enhancement of electron mobility and reduction of series resistance, leading to a significant increase in JSC; (3) almost no effect on VOC and FF. Ultimately, OSC devices based on PM6:BTP-eC9 with NDT-2 as the ETM achieved a remarkable PCE of 17.1% (a VOC of 0.839 V, a JSC of 28.2 mA cm-2 and FF of 72.1%), demonstrating superior photovoltaic performance compared to NDT-1 (PCE = 13.2%). This work discovered that the ester-modified NI molecules exhibit excellent alcohol solubility and film-forming ability, providing valuable insights for the development of NI molecules as efficient ETMs used in high-efficient OSCs
2024, 43(6): 100278
doi: 10.1016/j.cjsc.2024.100278
Abstract:
In this work, we have quantitatively simulated ISC rates and revealed the contributions from FC, HTVC and SVC effects for three types of TADF emitters. It is found that the impact of vibronic coupling varies among different molecular systems. For those with a significant local excitation, the direct ISC channel from FC contribution is unfavorable due to the large singlet-triplet energy gap. As such, the vibronic coupling effects can be substantial as reflected in the large HTVC and SVC terms. For the others having spatially separated HOMO and LUMO orbitals with an obvious CT excitation character, the singlet-triplet energy gap is usually small, and the FC term is thought to dominate the rate. However, even in this case, the HTVC and SVC cannot be neglected especially for the molecules with close alignment of Sn and Tn state energy levels. For instance, the SVC contribution to RISC rate for PTZ-DBTO2 can get to 32.6%. Finally, we have analyzed specific proportions of the contribution of different vibration modes to SVC, and it is reasonably inferred that the magnitude of SVC values can be controlled by shaping specific vibration modes, providing valuable insights for guiding molecular design strategies.
In this work, we have quantitatively simulated ISC rates and revealed the contributions from FC, HTVC and SVC effects for three types of TADF emitters. It is found that the impact of vibronic coupling varies among different molecular systems. For those with a significant local excitation, the direct ISC channel from FC contribution is unfavorable due to the large singlet-triplet energy gap. As such, the vibronic coupling effects can be substantial as reflected in the large HTVC and SVC terms. For the others having spatially separated HOMO and LUMO orbitals with an obvious CT excitation character, the singlet-triplet energy gap is usually small, and the FC term is thought to dominate the rate. However, even in this case, the HTVC and SVC cannot be neglected especially for the molecules with close alignment of Sn and Tn state energy levels. For instance, the SVC contribution to RISC rate for PTZ-DBTO2 can get to 32.6%. Finally, we have analyzed specific proportions of the contribution of different vibration modes to SVC, and it is reasonably inferred that the magnitude of SVC values can be controlled by shaping specific vibration modes, providing valuable insights for guiding molecular design strategies.
2024, 43(6): 100291
doi: 10.1016/j.cjsc.2024.100291
Abstract:
In summary, theoretical calculations and experimental analysis show that both π-conjugated organic cation with local polarity and tetravalent rare-earth cerium cations without lone pair electrons could be considered as good FBU for achieving a balance between SHG response and LIDT of metal halides, providing some unprecedented opportunities for designing novel NLO crystals. Additionally, integrating of a high coordination number of Zr4+ cation and a higher proportion of F atom would facilitate the acquisition of shorter UV cutoff edges. Therefore, we believe that if we can control the order arrangement and density of these microscopic groups in the crystal structure, the vigorous development of laser technology and its related fields will be undoubtedly promoted.
In summary, theoretical calculations and experimental analysis show that both π-conjugated organic cation with local polarity and tetravalent rare-earth cerium cations without lone pair electrons could be considered as good FBU for achieving a balance between SHG response and LIDT of metal halides, providing some unprecedented opportunities for designing novel NLO crystals. Additionally, integrating of a high coordination number of Zr4+ cation and a higher proportion of F atom would facilitate the acquisition of shorter UV cutoff edges. Therefore, we believe that if we can control the order arrangement and density of these microscopic groups in the crystal structure, the vigorous development of laser technology and its related fields will be undoubtedly promoted.
2024, 43(6): 100298
doi: 10.1016/j.cjsc.2024.100298
Abstract:
For many tandem chemical transformations utilizing H2O2 (and its intermediates), it's crucial to ensure that the rate of oxidant synthesis aligns with the secondary component's capacity to utilize the oxidant species for selective oxidation. This necessitates precise design and control of dual-functional catalysts to increase the utilization efficiency of H2, primarily through preventing H2O2 decomposition and competitive substrate hydrogenation. Another concern is associated with the increased cost of precious metals, which can be addressed by minimizing their loading or substituting them with less expensive metals while maintaining high production efficiency. Finally, further elucidation of the synergistic mechanism between metals and supports in dual-functional catalytic system is still needed, allowing for designing more active catalytic systems
For many tandem chemical transformations utilizing H2O2 (and its intermediates), it's crucial to ensure that the rate of oxidant synthesis aligns with the secondary component's capacity to utilize the oxidant species for selective oxidation. This necessitates precise design and control of dual-functional catalysts to increase the utilization efficiency of H2, primarily through preventing H2O2 decomposition and competitive substrate hydrogenation. Another concern is associated with the increased cost of precious metals, which can be addressed by minimizing their loading or substituting them with less expensive metals while maintaining high production efficiency. Finally, further elucidation of the synergistic mechanism between metals and supports in dual-functional catalytic system is still needed, allowing for designing more active catalytic systems
2024, 43(6): 100304
doi: 10.1016/j.cjsc.2024.100304
Abstract:
An organic-inorganic hybrid antimony(III) oxalate (C5H6ON)2[Sb2O(C2O4)3] has been successfully obtained by simultaneous combination of π-conjugated 4-hydroxypyridine and (C2O4)2– group with stereochemical active Sb(III) cation. The compound features a layered structure, and the equatorial planes of SbO6 units, π-conjugated (C2O4)2– and (C5H6ON)+ groups are closer to a planar arrangement, representing strong structural anisotropy that favors a large birefringence. As expected, (C5H6ON)2[Sb2O(C2O4)3] exhibits a large birefringence of 0.279 at 546 nm. Structural and theoretical analyses indicate that the combination of multiple π-conjugated units is a feasible approach for designing and exploring new superior birefringent materials.
An organic-inorganic hybrid antimony(III) oxalate (C5H6ON)2[Sb2O(C2O4)3] has been successfully obtained by simultaneous combination of π-conjugated 4-hydroxypyridine and (C2O4)2– group with stereochemical active Sb(III) cation. The compound features a layered structure, and the equatorial planes of SbO6 units, π-conjugated (C2O4)2– and (C5H6ON)+ groups are closer to a planar arrangement, representing strong structural anisotropy that favors a large birefringence. As expected, (C5H6ON)2[Sb2O(C2O4)3] exhibits a large birefringence of 0.279 at 546 nm. Structural and theoretical analyses indicate that the combination of multiple π-conjugated units is a feasible approach for designing and exploring new superior birefringent materials.
2024, 43(6): 100306
doi: 10.1016/j.cjsc.2024.100306
Abstract:
The remarkable optical characteristics exhibited by the supramolecular assembled solid powders have been extended to applications in display technology and 3D printing. Despite the substantial advancements achieved in this study, there remains considerable opportunity for further progress in comprehending the photophysics process of DP luminescence enhanced by supramolecular assembly. Additionally, further exploration is needed to understand the nature of interaction between the DPs and associated molecules. Given the efficient optical properties of DPs achieved through supramolecular assembly, there is considerable anticipation for the potential applications of this approach in diverse research fields, including solar cells, LED technology, and displays
The remarkable optical characteristics exhibited by the supramolecular assembled solid powders have been extended to applications in display technology and 3D printing. Despite the substantial advancements achieved in this study, there remains considerable opportunity for further progress in comprehending the photophysics process of DP luminescence enhanced by supramolecular assembly. Additionally, further exploration is needed to understand the nature of interaction between the DPs and associated molecules. Given the efficient optical properties of DPs achieved through supramolecular assembly, there is considerable anticipation for the potential applications of this approach in diverse research fields, including solar cells, LED technology, and displays
2024, 43(6): 100308
doi: 10.1016/j.cjsc.2024.100308
Abstract:
In addition, catalyst stability is of pressing concern. Some other approaches have been proposed to prevent supported metal NPs sintering, such as metal species confined in zeolites (metal@zeolite) or construction of strong metal-support interaction (SMSI) on the reducible supports in many cases. However, the poor accessibility of encapsulated metal species to reactants with large molecular size might slow the reaction for metal@zeolite catalysts, and the catalyst activity would be sacrificed due to the coverage of metal oxide on the active metal NPs surface for catalysts with SMSI effect. In contrast, this work shows a successful example for the construction of stable supported metal NPs catalyst using defect rich zeolites surface, which overcomes the challenge of Cu NPs sintering during the reaction atmosphere. The diffusion issues can be avoided because active Cu species are anchored on the Beta-deAl zeolite surface, and most Cu NPs are stabilized with uncovered metal surface. Other strategies to introduce defect sites in zeolites and the stability of metal NPs over such modified zeolites under reaction conditions need further investigations. We believe that more excellent works in the future are expected to the development of zeolite-based metal catalysis.
In addition, catalyst stability is of pressing concern. Some other approaches have been proposed to prevent supported metal NPs sintering, such as metal species confined in zeolites (metal@zeolite) or construction of strong metal-support interaction (SMSI) on the reducible supports in many cases. However, the poor accessibility of encapsulated metal species to reactants with large molecular size might slow the reaction for metal@zeolite catalysts, and the catalyst activity would be sacrificed due to the coverage of metal oxide on the active metal NPs surface for catalysts with SMSI effect. In contrast, this work shows a successful example for the construction of stable supported metal NPs catalyst using defect rich zeolites surface, which overcomes the challenge of Cu NPs sintering during the reaction atmosphere. The diffusion issues can be avoided because active Cu species are anchored on the Beta-deAl zeolite surface, and most Cu NPs are stabilized with uncovered metal surface. Other strategies to introduce defect sites in zeolites and the stability of metal NPs over such modified zeolites under reaction conditions need further investigations. We believe that more excellent works in the future are expected to the development of zeolite-based metal catalysis.
2024, 43(6): 100310
doi: 10.1016/j.cjsc.2024.100310
Abstract:
What is clear from this research article is that there is a significant progress for preparing highly interconnected zeolites with extra-stable extra-large-pore, which is a dream in the past decades. However, is it possible to scale up these extra-stable extra-large-pore zeolites for commercial application? One of the important factors is to reduce the synthesis cost, and one of the solutions is to synthesize these zeolites in the presence of low-cost organic templates even in the absence of organic templates. The fact that the synthesis of dream zeolites with extra-stable extra-large-pore would give a new chance for both fundamental and applied research of zeolites.
What is clear from this research article is that there is a significant progress for preparing highly interconnected zeolites with extra-stable extra-large-pore, which is a dream in the past decades. However, is it possible to scale up these extra-stable extra-large-pore zeolites for commercial application? One of the important factors is to reduce the synthesis cost, and one of the solutions is to synthesize these zeolites in the presence of low-cost organic templates even in the absence of organic templates. The fact that the synthesis of dream zeolites with extra-stable extra-large-pore would give a new chance for both fundamental and applied research of zeolites.
2024, 43(6): 100323
doi: 10.1016/j.cjsc.2024.100323
Abstract:
In summary, we obtained a centimeter-scale elastic crystal responsive to pressure using EPC. Analysis of single-crystal data, energy framework, etc., revealed that internal interactions, particularly C–H⋯π, C–H⋯N and C–H⋯S, buffer deformation. Under hydrostatic pressure, the crystals exhibited color and luminescence changes, including a bathochromic redshift and fluorescence enhancement attributed to RIM and increased π-π interactions. Upon pressure release, the fluorescence intensity reverted with 90% of the initial value, indicating reversible pressure-dependent luminescence. These findings highlight the potential of EPC for flexible smart high-pressure sensors and contribute to advances in responsive optics.
In summary, we obtained a centimeter-scale elastic crystal responsive to pressure using EPC. Analysis of single-crystal data, energy framework, etc., revealed that internal interactions, particularly C–H⋯π, C–H⋯N and C–H⋯S, buffer deformation. Under hydrostatic pressure, the crystals exhibited color and luminescence changes, including a bathochromic redshift and fluorescence enhancement attributed to RIM and increased π-π interactions. Upon pressure release, the fluorescence intensity reverted with 90% of the initial value, indicating reversible pressure-dependent luminescence. These findings highlight the potential of EPC for flexible smart high-pressure sensors and contribute to advances in responsive optics.
2024, 43(6): 100324
doi: 10.1016/j.cjsc.2024.100324
Abstract:
SAMs with tunable permanent dipole that could alter the WF of the substrate seem to be a perfect alternative to the thick HTLs in inverted PSCs. Essential elements are present in their simple structures to achieve efficient energy level alignment and hole extraction/transport. More importantly, the simplified fabrication process represents the direction towards cost-efficient production of end products. The success of SAMs in inverted PSCs should inspire the perovskite community in two directions: 1. There should exist n-type counterparts that can change the WF of the substrate toward the opposite direction so that an efficient electron extraction/injection could be achieved without using an independent electron transporting layer; 2. A more stable inorganic compound with essential capability of modulating the WF of conductive electrodes should be the final target to realize efficient and truly stable PSCs. Nowadays, passivation is ubiquitous for achieving high-performance inverted PSCs. However, dipolar SAMs, designed to replace the traditional HTLs, such as PTAA or NiO, have not yet shown a consistent passivation effect at the perovskite buried interface. Therefore, besides the dipole moment, it will be also beneficial to carefully design structurally specific SAMs with apparent passivation efficacy. However, whether such efforts will fall into the category of over-engineering deserves further exploration. These topics remain crucial for further investigation, which demands substantial research dedication and commitment.
SAMs with tunable permanent dipole that could alter the WF of the substrate seem to be a perfect alternative to the thick HTLs in inverted PSCs. Essential elements are present in their simple structures to achieve efficient energy level alignment and hole extraction/transport. More importantly, the simplified fabrication process represents the direction towards cost-efficient production of end products. The success of SAMs in inverted PSCs should inspire the perovskite community in two directions: 1. There should exist n-type counterparts that can change the WF of the substrate toward the opposite direction so that an efficient electron extraction/injection could be achieved without using an independent electron transporting layer; 2. A more stable inorganic compound with essential capability of modulating the WF of conductive electrodes should be the final target to realize efficient and truly stable PSCs. Nowadays, passivation is ubiquitous for achieving high-performance inverted PSCs. However, dipolar SAMs, designed to replace the traditional HTLs, such as PTAA or NiO, have not yet shown a consistent passivation effect at the perovskite buried interface. Therefore, besides the dipole moment, it will be also beneficial to carefully design structurally specific SAMs with apparent passivation efficacy. However, whether such efforts will fall into the category of over-engineering deserves further exploration. These topics remain crucial for further investigation, which demands substantial research dedication and commitment.
