2D Halide Perovskites Research Articles

Deterministic fabrication of 3D/2D perovskite bilayer stacks for durable and efficient solar cells.

Realizing solution-processed heterostructures is a long-enduring challenge in halide perovskites because of solvent incompatibilities that disrupt the underlying layer. By leveraging the solvent dielectric constant and Gutmann donor number, we could grow phase-pure two-dimensional (2D) halide perovskite stacks of the desired composition, thickness, and bandgap onto 3D perovskites without dissolving the underlying substrate. Characterization reveals a 3D-2D transition region of 20 nanometers mainly determined by the roughness of the bottom 3D layer. Thickness dependence of the 2D perovskite layer reveals the anticipated trends for n-i-p and p-i-n architectures, which is consistent with band alignment and carrier transport limits for 2D perovskites. We measured a photovoltaic efficiency of 24.5%, with exceptional stability of T99 (time required to preserve 99% of initial photovoltaic efficiency) of >2000 hours, implying that the 3D/2D bilayer inherits the intrinsic durability of 2D perovskite without compromising efficiency.

Stereochemically Active Lone Pairs and Nonlinear Optical Properties of Two-Dimensional Multilayered Tin and Germanium Iodide Perovskites.

Two-dimensional (2D) metal halide perovskites are promising tunable semiconductors. Previous studies have focused on Pb-based structures, whereas the multilayered Sn- and Ge-based analogues are largely unexplored, even though they potentially exhibit more diverse structural chemistry and properties associated with the more polarizable ns2 lone-pair electrons. Herein, we report the synthesis and structures of 2D tin iodide perovskites (BA)2(A)Sn2I7, where BA = n-butylammonium and A = methylammonium, formamidinium, dimethylammonium, guanidinium, or acetamidinium, and those of 2D germanium iodide perovskites (BA)2(A)Ge2I7, where A = methylammonium or formamidinium. By comparing these structures along with their Pb counterparts, we establish correlations between the effect of group IV-cation's lone-pair stereochemical activity on the perovskite crystal structures and the resulting semiconducting properties such as bandgaps and carrier-phonon interactions and nonlinear optical properties. We find that the strength of carrier-phonon interaction increases with increasing lone-pair activity, leading to a more prominent photoluminescence tail on the low-energy side. Moreover, (BA)2(A)Ge2I7 exhibit strong second harmonic generation with second-order nonlinear coefficients of ∼10 pm V-1 that are at least 10 times those of Sn counterparts and 100 times those of Pb counterparts. We also report the third-order two-photon absorption coefficients of (BA)2(A)Sn2I7 to be ∼10 cm MW-1, which are one order of magnitude larger than those of the Pb counterparts and traditional inorganic semiconductors. These results not only highlight the role of lone-pair activity in linking the compositions and physical properties of 2D halide perovskites but also demonstrate 2D tin and germanium iodide perovskites as promising lead-free alternatives for nonlinear optoelectronic devices.

Strain propagation in layered two-dimensional halide perovskites.

Impulsive light excitation presents a powerful tool for investigating the interdependent structural and electronic responses in layered two-dimensional (2D) halide perovskites. However, detailed understanding of the nonlinear lattice dynamics in these soft hybrid materials remains limited. Here, we explicate the intrinsic strain propagation mechanisms in 2D perovskite single crystals using transient reflection spectroscopy. Ultrafast photoexcitation leads to the generation of strain pulses via thermoelastic (TE) stress and deformation potential (DP) interaction whence their detection proceed via Brillouin scattering. Using a two-temperature model together with strain wave propagation, we discern the TE and DP contributions in strain generation. Hot carrier cooling plays a dominant role in effecting the weak modulation amplitude. Out-of-plane lattice stiffness is reduced by the weak van der Waals bond between organic layers, resulting in a slow strain propagation velocity. Our findings inject fresh insights into the basic strain properties of layered perovskites critical for manipulating their functional properties for new applications.

Switchable Color Semiconductors: Methylamine Intercalation, Deintercalation, and Retention in Two-Dimensional Halide Perovskites

The low formation energy of metal halide perovskites (MHPs) and their high performance in optoelectronic applications make them rather interesting semiconductor materials. In this work, we take advantage of the tunability of two-dimensional (2D) halide perovskites of the type A2PbI4 to explore a chromogenic mechanism in these materials where methylamine is allowed to intercalate into and deintercalate from the halide perovskite films. Methylamine intercalation results in a change in color from the initial yellow/orange color of the A2PbI4 films to visibly transparent films, while deintercalation leads to a return of a colored film. The reversibility of this solvatochromic mechanism was found to be highly dependent on the nature of the A-site cation used. We observe the formation of iodoplumbate phases, mixed 2D/three-dimensional (3D) perovskites, and/or 3D perovskites as secondary phases formed in some systems and, by exploring a wide array of A2PbI4 materials, we identify key design rules for the A-site cation to limit secondary phase formation and structural changes associated with methylamine intercalation/deintercalation. Specifically, the effects of changing cation–cation, cation “head”-inorganic, and cation “tail”-inorganic interactions in this system are demonstrated. By carefully controlling these interactions, more robust solvatochromic systems are realized. These initial explorations of metal halide solvatochromism improve the understanding of A-site cation design in A2PbI4 MHPs and show that these are a promising class of solvatochromic semiconductors.

Improving the performance of 2D perovskite solar cells by carrier trappings and minifying the grain boundaries

Fabrication of 2D perovskite layers on 3D perovskite light absorbers, as the perovskite solar cells (PSCs), is being exploited to achieve a high power-conversion efficiency (PCE) along with promising long-term stability. However, to improve the performance of PSCs, an intermediate layer of smart material is required which can facilitate the desired interaction between two perovskite layers. The present work explores the role of 4-methoxyphenethylammonium (MPA+) cations as interfacing layer in 2D halide perovskite material towards developing an efficient PSCs. The effect of different ammonium salts (NH4Cl and NH4SCN) as additives in mixed halide MPA0.2MA0.8PbI3 is examined and the optoelectronic and photovoltaic responses of the developed PSCs are investigated in detail. Mixed halide MPA0.2MA0.8PbI3 thin film processed with NH4SCN additive showed an improved morphological and crystalline properties of fabricated PSCs as well as reduced non-radiative charge-carrier recombination rate. The NH4SCN/MPA0.2MA0.8PbI3 thin film based PSC demonstrated the highest PCE of ~15.1%, which is nearly 10% higher as compared to that of control PSC sample (~13.7%) and NH4Cl/MPA0.2MA0.8PbI3 thin film PSC (~7.53%). The NH4SCN/MPA0.2MA0.8PbI3 based PSC with highest efficiency, additionally showed a significantly improved device stability. It retained an efficiency value of ~95% of its initial even after exposure to ambient condition upto 300 h. The presented NH4SCN/MPA0.2MA0.8PbI3 thin film based PSC with high efficiency and high stability could open new avenues for improving the performance of solar cells and increase their contribution towards generation of renewable energy in future.

Graphene protection improves the stability of two‐dimensional halide perovskites under the electron irradiation

The crystal structure of two-dimensional (2D) organic-inorganic halide perovskites undergoes fast structural collapse under the electron beam irradiation, hindering high-resolution transmission electron microscopy imaging. Graphene protection is an effective solution to mitigate the damage of electron-beam irradiation and has been applied in 2D materials such as MoS2 . However, the effectivity of graphene protection has not been demonstrated in 2D halide perovskites yet, as traditional wet-transfer of graphene with aqueous solution would cause serious degradation for moisture-sensitive halide perovskites. Here, we verified that graphene protection plays a protection role and developed a method using nonpolar solvent to transfer the graphene layer atop the perovskite nanosheets. With this method, the perovskite nanosheets might be well protected by graphene encapsulation. HIGHLIGHTS: Transfer method of graphene on moisture-sensitive 2D halide perovskites using nonpolar solvents was developed. Graphene substrate is proven to be able to mitigate electron-beam damage to 2D halide perovskites. Encapsulation structure of graphene/halide perovskite/graphene was demonstrated.

Photoluminescent Properties of Two-Dimensional Manganese(II)-Based Perovskites with Different-Length Arylamine Cations.

The participation of organic cations plays an important role in tuning broad-spectra emissions. Herein, we synthesized a series of Mn(II)-based two-dimensional (2D) halide perovskites with arylamine cations of different lengths having the general formula (C6H5(CH2)xNH3)2MnCl4 (x = 1-4), with the x = 4 compound reported here for the first time. With the increase in the -(CH2)- in organic cations, the distance between adjacent inorganic layers increases, causing the title compounds to exhibit different structural distortions. As the Mn-Cl-Mn angular distortion increases, the experimental optical band gaps of the title compounds increase correspondingly. When the angle distortion between the octahedrons of the compounds is similar, the band gaps may also be affected by the distortion of the octahedron itself (the bond-length distortion of 2 is greater than that of 4). Under UV-light irradiation at 298 K, all of the compounds exhibit two emission peaks centered at 480-505 and 610 nm, corresponding to the organic-cation emission and the 4T1(G) to 6A1(S) radiative transition of Mn2+ ions, respectively. Among these title compounds, (PPA)2MnCl4 [(PPA)+ = C6H5(CH2)3NH3+] exhibits the strongest photoluminescence (PL). The study of the title compounds contributes to an in-depth understanding of the relationship between the structural distortion and optical properties of 2D Mn(II)-based perovskite materials.

Ordered Mixed-Spacer 2D Bromide Perovskites and the Dual Role of 1,2,4-Triazolium Cation

Two-dimensional (2D) halide perovskites exhibit extraordinary stability and structural diversity because they can incorporate different organic cations (both cage A-site cation and the spacers). Here, we report on the behavior of Tz = 1,2,4-triazolium as an A-site cation as well as a spacer cation in new perovskite compounds. We describe the synthesis and structure–property relationships of a new family of hydrogen-bonding stabilized 2D perovskites (IPA)2(Tz)n−1PbnBr3n+1 (n = 1–3) (IPA = isopropylammonium, Tz = 1,2,4-triazolium), which represents the rare example of 2D perovskites incorporating the large A-site cation (Tz) that can form both the n = 2 and 3 phases. However, excess of Tz cations can split the n = 2 layers to act as a spacer and combine with another spacer PA (PA = propylammonium) or BA (BA = butylammonium) to form n = 1 structures (PA)(Tz)PbBr4 and (BA)(Tz)PbBr4. These ordered mixed-spacer perovskites with different interlayer distances are unusual because the different spacers tend to stay in the same interlayer. (IPA)2(Tz)n−1PbnBr3n+1 all exhibit broad photoluminescence emission but for different reasons. For the n = 1 phase, the large octahedral tilting (small Pb–Br–Pb angle) gives rise to the broad emission, while for the n = 2 and 3 phases, the individual octahedral distortion (large distortion index) plays a more important role. For the mixed-spacer (PA)(Tz)PbBr4 and (BA)(Tz)PbBr4, their band gaps are in between the parent n = 1 compounds [(BA)2PbBr4 or (PA)2PbBr4, and (Tz)2PbBr4]. Density functional theory calculations suggest that the band structures of (PA)(Tz)PbBr4 and (BA)(Tz)PbBr4 combine features from both parent compounds yet differ from a simple superposition. This work demonstrates the dual role of Tz molecules as the A-site cation in multilayer 2D perovskites and as the spacer in ordered mixed-spacer 2D phases.

Metal-cation-mixed lead-less two-dimensional hybrid perovskites with high carrier mobility and promoted light adsorption

The metal cation mixing in hybrid perovskite has been suggested as an effective strategy not only to promote the performance and stability but also to reduce the content of toxic lead element for environmental and health concerns. However, such a strategy has yet been well demonstrated in two-dimensional (2D) hybrid perovskites with multilayered thickness (n > 1). Here, we theoretically investigated the lead-less and lead-free 2D hybrid perovskites with tin-lead (Sn–Pb) and germanium-tin (Ge–Sn) mixed metal cations, namely, the BA2MAn-1Snn/2Pbn/2I3n+1 and BA2MAn-1Gen/2Snn/2I3n+1 (BA: C4H9NH3+; n = 1–4), by means of first-principle calculations. It is found that the electronic structure and light absorption properties of the 2D hybrid perovskites can be efficiently tuned to the optimal range for solar cells by combining the metal cations mixing and the layer thickness (n) adjustment. Markedly, due to the enhanced in-plane elastic modulus but greatly reduced deformation potential constant, both the Ge–Sn and Sn–Pb mixed 2D perovskites show high carrier mobility (∼103−104 cm2V–1S−1), which are superior to that of their 3D analogues. Moreover, the Sn–Pb mixed 2D perovskites expose much stronger visible light absorption than the non-mixed Sn- or Pb-based 2D perovskites. In addition, the in-air stability of metal-cation-mixed 2D hybrid perovskites are greatly improved compared to the 3D halide perovskites. This work suggests the great potential of the metal-cation-mixed 2D hybrid perovskite for photovoltaic and optoelectronic applications with largely reduced lead content.

Light-Controlled Reconfigurable Optical Synapse Based on Carbon Nanotubes/2D Perovskite Heterostructure for Image Recognition.

Two-dimensional (2D) halide perovskite material is characterized by a mixed conducting behavior that possesses both electronic and ionic conductivity. The study on the influence of the light on ion migration in the 2D perovskite is helpful to improve the performance of perovskite-based optoelectronic devices. Here, we constructed an exfoliated 2D perovskite/carbon nanotubes (CNTs) heterostructure optical synapse, in which CNTs can be used as nanoprobes to qualitatively observe the ion aggregation or dissipation process in 2D perovskite, and found that light significantly changes the memory curve of the reconfigurable optical synapses. Through the molecular dynamic simulation, the dynamic process of ion migration in the heterostructure was simulated and the electrostatic interaction effect of nonequilibrium charge distribution of CNTs on iodide ion was demonstrated. Finally, an effective light-controlled process was realized through the synapses, which in situ regulated the performance of the weight-value discretized BP (WD-BP) neural network. This work lays a foundation for the future development of intelligent nano-optoelectronic devices.

Photo de-mixing in Dion-Jacobson two-dimensional mixed halide perovskites

Two-dimensional (2D) halide perovskites feature a versatile structure, which not only enables the fine-tuning of their optoelectronic properties but also makes them appealing as model systems to investigate the fundamental properties of hybrid perovskites. In this study, we analyzed the changes in the optical absorption of 2D Dion-Jacobson mixed halide perovskite thin films (encapsulated) based on (PDMA)Pb(I0.5Br0.5)4 (PDMA: 1,4-phenylenedimethanammonium spacer) exposed to a constant illumination. We demonstrate that these 2D mixed-halide perovskites undergo photo de-mixing with direct transformation from the pristine phase to the de-mixed phases. Almost complete re-mixing of these phases occurs when the sample is left in the dark, showing that the process is reversible in terms of optical properties. On the other hand, exposure to light appears to induce structural changes in the thin film that are not reversible in the dark. We have further investigated temperature-dependent absorption measurements under light to extract the photo de-mixed compositions and to map the photo-miscibility-gap. This work thereby reveals that photo de-mixing occurs in Dion-Jacobson two-dimensional hybrid perovskites and provides strategies to address the role of light in the thermodynamic properties of these materials.

Entropy Stabilization Effects and Ion Migration in 3D "Hollow" Halide Perovskites.

A recently discovered new family of 3D halide perovskites with the general formula (A)1-x(en)x(Pb)1-0.7x(X)3-0.4x (A = MA, FA; X = Br, I; MA = methylammonium, FA = formamidinium, en = ethylenediammonium) is referred to as "hollow" perovskites owing to extensive Pb and X vacancies created on incorporation of en cations in the 3D network. The "hollow" motif allows fine tuning of optical, electronic, and transport properties and bestowing good environmental stability proportional to en loading. To shed light on the origin of the apparent stability of these materials, we performed detailed thermochemical studies, using room temperature solution calorimetry combined with density functional theory simulations on three different families of "hollow" perovskites namely en/FAPbI3, en/MAPbI3, and en/FAPbBr3. We found that the bromide perovskites are more energetically stable compared to iodide perovskites in the FA-based hollow compounds, as shown by the measured enthalpies of formation and the calculated formation energies. The least stable FAPbI3 gains stability on incorporation of the en cation, whereas FAPbBr3 becomes less stable with en loading. This behavior is attributed to the difference in the 3D cage size in the bromide and iodide perovskites. Configurational entropy, which arises from randomly distributed cation and anion vacancies, plays a significant role in stabilizing these "hollow" perovskite structures despite small differences in their formation enthalpies. With the increased vacancy defect population, we have also examined halide ion migration in the FA-based "hollow" perovskites and found that the migration energy barriers become smaller with the increasing en content.

Spacer Organic Cation Engineering for Quasi‐2D Metal Halide Perovskites and the Optoelectronic Application

Recently, organic and inorganic halide perovskites are one of the most popular semiconductors owing to their enormous potential for optoelectronic application, such as photovoltaics (PV), light‐emitting diode (LED), photodetector, and so on. The photoelectric conversion efficiency of 3D organic–inorganic hybrid perovskite solar cells has increased rapidly; however, the commercialization of the related devices is largely hampered by the poor stability of perovskite materials under environmental stress. Compared to 3D halide perovskites, quasi‐2D (Q‐2D) perovskites have improved moisture stability and less tendency for ion migration, which offers a new approach to stabilize perovskite‐based optoelectronic devices. Furthermore, Q‐2D hybrid perovskites have diverse structures with different quantum confinement and dielectric confinement characteristics, which enables the fine‐tuning of their optoelectronic properties through structure engineering. Depending on the different structures of spacer organic cations, the Q‐2D perovskite structure mainly includes Ruddlesden−Popper (RP) phase structure, Dion−Jacobson (DJ) phase structure, and alternating cation in the interlayer space (ACI) phase structure. In this review, the state‐of‐the‐art in Q‐2D perovskites is discussed based on their structural engineering, and an overview of PV and LEDs applications is provided. Finally, a brief outlook with respect to the development of Q‐2D perovskite materials, as well as advanced device, is provided.

Correlated Dynamics of Free and Self‐Trapped Excitons and Broadband Photodetection in BEA2PbBr4 Layered Crystals

AbstractSelf‐trapped excitons (STEs) exert a profound impact on the optical properties and device applications of 2D halide perovskites. Particularly distinct exciton self‐trapping and detrapping processes can facilitate the intelligent design of perovskite optoelectronic devices with emerging functionalities. Thus, a comprehensive understanding and regulation of exciton trapping and detrapping dynamics are highly desired. Herein, the authors report a 2D lead halide perovskite (BEA2PbBr4 where BEA is 2‐bromine ethylamine) with exceptional broadband photoluminescence (PL), which originates from multiple STE states. In particular, the unique energy‐level configuration of STEs with respect to free excitons is revealed by exploiting optical spectroscopy. Consequently, these distinct phenomena empower the broadband photodetection capability of BEA2PbBr4 photodetectors over a wide range from ultraviolet to near‐infrared wavelengths. These results provide an essential understanding of the intriguing photophysics of STEs and shed new light on the future development of single‐component perovskite broadband optoelectronic devices.

Elucidating the Unique Hot Carrier Cooling in Two-Dimensional Inorganic Halide Perovskites: The Role of Out-of-Plane Carrier–Phonon Coupling

Two-dimensional (2D) halide perovskites represent the natural semiconductor quantum wells (QWs), which hold great promise for optoelectronics. However, due to the hybrid structure of Ruddlesden-Popper 2D perovskites, the intrinsic nature of hot-carrier kinetics remains shielded within. Herein, we adopt CsPbBr3 nanoplates as a model system to reveal the intrinsic carrier dynamics in inorganic perovskite QWs. Interestingly, we revealed an ultrafast and hot-phonon-bottleneck (HPB)-free carrier cooling in monodisperse CsPbBr3 QWs, which is in sharp contrast to the bulk and nanocrystalline perovskites. The absence of HPB was attributed to the efficient out-of-plane triplet-exciton-LO-phonon coupling in 2D perovskites because of the structural anisotropy. Accordingly, the HPB can be activated by shutting down the out-of-plane energy loss route through forming the layer-stacked perovskite superlattice. The controllable on and off of HPB may provide new possibilities in optoelectronic devices and these findings deepen the understanding of a hot-carrier cooling mechanism in 2D perovskites.

2D Pb‐Halide Perovskites Can Self‐Heal Photodamage Better than 3D Ones

AbstractAdding a 2D character to halide perovskite (HaP) active layers in ambient‐protected cells can improve their stability drastically, which is not obvious from the hydrophobicity of the large cations that force the HaP into a 2D structure. Results of two‐photon confocal microscopy are reported to study inherent photo‐stability of 2D Pb iodide HaPs in the interior of single crystals. Compared to 3D HaP crystals, 2D ones have higher photo‐stability and, under a few sun‐equivalent conditions, self‐heal efficiently after photo‐damage. Using both photoluminescence (PL) intensities (as function of time after photo‐damage) and spectra, self‐healing dynamics of 2D HaP (C4H9NH3)2PbI4, 2D/3D (C4H9NH3)2(CH3NH3)2Pb3I10 and 3D MAPbI3 are compared. Differences in response to photo‐damage and self‐healing ability from different degrees of photo‐damage are found between these HaPs. Based on the findings, a possible chemical mechanism for photo‐damage and self‐healing of the 2D HaPs is suggested: the layered lattice arrangement limits out‐diffusion of degradation products, facilitating damage reversal, leading to better 2D HaP photo‐stability and self‐healing uniformity than for 2D/3D HaPs. One implication of the layered structures’ resilience to photo‐damage is transfer of their increased stability to devices made with them, such as photovoltaic solar cells and light‐emitting diodes.

Realization of Polaritonic Topological Charge at Room Temperature Using Polariton Bound States in the Continuum from Perovskite Metasurface (Advanced Optical Materials 6/2022)

In article number 2102386, Hai Son Nguyen and co-workers demonstrate experimentally polariton bound states in the continuum (“pol-BICs”) in an excitonic metasurface based on 2D halide perovskite. These hybrid light–matter states, operating at room temperature, exhibit all peculiar features of BICs: a total uncoupling from the radiative continuum associated to an infinite radiative quality factor, and a topological charge associated to a polarization singularity in the farfield emission.

Mechanochromic Luminescence of Composites Based on (CH3NH3)PbBr3 and Layered HPs: Influence of 2D Components and Interface Multilayered Phases

AbstractThe mechanochromic luminescence (MCL) properties of crystallized powders of composites based on the 3D perovskite MAPbBr3 and one layered (2D) halide perovskite (HP) are reported for three 2D HPs selected for their distinct emission properties: (PEA)2PbBr4 (n=1) narrow emission (HE), (EDBE)PbBr4 (m=2) broad emission (LE) and (BA)2PbBr4 (n=1) dual emission (HE and LE). All composites exhibit sensitive MCL due to the activation of the 3D component emission through energy transfer (ET) from multilayered perovskites formed at the interface. While the excitonic HE band is less affected by the mechanical treatment, LE is quenched in crushed composites, suggesting that it rather originates from the crystal edge/surfaces. Full reversibility of the MCL process is obtained only when the multilayered phases formed at the interface are not stable. The emission of composite thin films, where larger 2D/3D interface areas are present, further support the role of the interfaces in the activation of 3D emission.

Band gap, effective masses, and energy level alignment of 2D and 3D halide perovskites and heterostructures using DFT-1/2

We revisit the Slater half-occupation technique within the DFT-1/2 method to provide improved accuracy of 2D and 3D halide perovskites band gaps at a moderate computational cost. We propose an electron removal scheme from the halide states that drastically improve the predicted band gaps of 2D compounds. Concurrently, we compute the effective masses of the considered structures and show that DFT-1/2 describes them with a nice degree of accuracy when compared to available experimental data. Moreover, we assess the suitability of DFT-1/2 to compute the energy level alignments of this family of compounds. We compare the results in light of those we predict using the hybrid functional HSE06 and the many body perturbation theory within the $G0W0$ approximation. We discuss the limitations of our refined DFT-1/2 scheme, which tends to overestimate the downshift of the absolute valence energy levels of the layered perovskite systems. We anticipate that our results would be useful to initiate benchmark studies and investigate large systems such as heterostructures for which other approaches may be out of reach.

Two-Dimensional Dion-Jacobson Perovskite (NH3C4H8NH3)CsPb2Br7 with High X-ray Sensitivity and Peak Discrimination of α-Particles.

Two-dimensional (2D) halide perovskites have attracted extensive interest because of their excellent optoelectronic properties, structural diversity, and promising stability. Herein, we grow a novel 2D Dion-Jacobson halide perovskite, (BDA)CsPb2Br7 (BDA = 1,4-butanediamine, NH3C4H8NH32+), which exhibits a large bandgap (∼2.76 eV), high resistivity (∼4.35 × 1010 Ω·cm), and considerable switching ratio (>700), indicating great potential for radiation detection. Both experimental and calculated results demonstrate that (BDA)CsPb2Br7 has a significantly improved mobility compared to those of Ruddlesden-Popper perovskites (BA)2CsPb2Br7 and (i-BA)2CsPb2Br7, which is attributed to the shorter interlayer distance leading to the enhanced orbital interactions. The resulting (BDA)CsPb2Br7 detector along the out-of-plane direction achieves a high X-ray sensitivity of 725.5 μC·Gy-1·cm-2. Another fascinating attribute is that the detector exhibits good peak discrimination with an energy resolution of ∼37% when illuminated by the 241Am@5.48 MeV α-particles under a negative bias of 260 V. These results provide a broad prospect for 2D Dion-Jacobson perovskites for future radiation detection applications.