Low Amplified Spontaneous Emission Threshold Research Articles

Optical and Amplified Spontaneous Emission Properties of 4H-Pyran-4-Ylidene-2-Cyanoacetate Fragment Containing 2-Cyanoacetic Acid Derivative in PVK, PSU, or PS Matrix

Organic solid-state lasers are highly promising devices known for their low-cost fabrication processes and compact sizes and the tunability of their emission spectrum. These lasers are in high demand across various industries including biomedicine, sensors, communications, spectroscopy, and military applications. A key requirement for light-emitting materials used in a light-amplifying medium is a low threshold value of the excitation energy of the amplified spontaneous emission (ASE). A newly synthesized non-symmetric red-light-emitting laser dye, Ethyl 2-(2-(4-(bis(2-(trityloxy)ethyl)amino)styryl)-6-tert butyl-4H-pyran-4-ylidene)-2-cyanoacetate (KTB), has shown great promise in meeting this requirement. KTB, with its attached bulky trityloxyethyl groups, has the ability to form amorphous thin films from a solution using a wet-casting method. Recent experiments have demonstrated that KTB exhibits a low ASE threshold value. This study focused on investigating the optical and amplified spontaneous emission properties of KTB in poly(N-vinylcarbazole) (PVK), polysulfone (PSU), and polystyrene (PS) matrices at various concentrations. The results showed that as the concentration of the dye increased, a redshift of the photoluminescence and ASE spectra occurred due to the solid-state solvation effect. The lowest ASE threshold value of 9 µJ/cm2 was achieved with a 20 wt% concentration of KTB in a PVK matrix, making it one of the lowest excitation threshold energies reported to date.

End Cap Effect on Solution-Processable Deep Blue Lasing Materials with Low-Amplified Spontaneous Emission Thresholds.

Organic lasers have attracted increasing attention owing to their superior characteristics such as lightweight, low-cost manufacturing, high mechanical flexibility, and high emission-wavelength tunability. Recent breakthroughs include electrically pumped organic laser diodes and an electrically driven organic laser, integrated with an organic light-emitting diode pumping. However, the availability of efficient deep blue organic laser chromophores remains limited. In this study, we develop two novel rigid oligophenylenes, end-capped with carbazole and phenylcarbazole groups, to demonstrate exceptional optical and amplified spontaneous emission (ASE) properties. These oligophenylenes are not only solution processable but also exhibit remarkably high solution photoluminescence quantum yields (PLQYs) of 90% and high radiative rates of 1.35 × 109 s-1 in the deep blue range. Our theoretical calculations confirm that the carbazole and phenylcarbazole end groups play a pivotal role in enhancing the optical transitions of the oligophenylene laser chromophores, thereby elevating their emission oscillator strengths. Remarkably, these materials demonstrate low solid-state ASE threshold values of 1.0 and 1.5 μJ/cm2 (at 431 and 418 nm, respectively). To the best of our knowledge, these ASE thresholds represent the lowest reported at these specific ASE wavelengths in the literature, regardless of whether they are solution-processed or thermally evaporated films. Furthermore, they exhibit excellent thermal and photostability, low triplet quantum yields, as well as negligible overlap of excited-state absorption within the ASE emission region, making them excellent candidates for a new class of deep blue materials for organic lasers. By integrating insights from theoretical calculations and experimental validation, our study provides a comprehensive understanding of the design principles behind these high-performing organic laser chromophores, paving the way for the development of advanced organic lasers with enhanced performance characteristics.

Extremely Low Threshold Quasi‐CW Amplified Spontaneous Emission Achieving and Its Mechanism Study

AbstractThe development of lasing materials with weak pile‐up effect from triplet excitons, low lasing threshold, and long operational lifetime is much significant for truly continuous wave operation and electrically pumping organic lasers. However, most of organic gain media has been verified to have extreme quenching effect from triplet excitons due to its wide‐band distribution of triplet absorption spectrum. Here, it is found that the phenanthroimidazole derivatives as gain media have congenital advantages on handling triplet's issues. A very low amplified spontaneous emission (ASE) threshold of 0.56 µJ cm−2 and a long operational lifetime of 5.77 × 105 pump pulses in air atmosphere are well obtained. When increasing the pump repetition frequency from 20 Hz to 20 kHz, the operational lifetimes of the thin films have small reduction. Under a high pump repetition frequency of 200 kHz, which is quasi‐continuous wave operational regime, the PI2PhDPO thin film exhibits very low ASE threshold of 0.78 µJ cm−2 due to the tiny overlap between triplet absorption and ASE spectra.

The enhanced properties of amplified spontaneous emission and organic light emitting diodes based on Ag NPs doped hole transfer layer

The organic semiconductor lasers (OSLs) have been seen as a promising light source for future applications. Lower amplified spontaneous emission (ASE) threshold of the organic gain medium and optimized device structures are key factors to realize electrically pumped OSLs. In this paper, the silver nanoparticles (Ag NPs) doped PEDOT: PSS buffer layer was used to improve the ASE performance of BUBD-1 molecule and the optoelectronic performance of the corresponding organic light-emitting diodes (OLEDs). Compared with the reference device with pure PEDOT: PSS buffer layer, the lowest ASE threshold was obtained in CBP: 45 wt%BUBD-1 blend film at the optimal volume ratio 1:3 of PEDOT: PSS: Ag NPs, decreased by 6 times. Then the Ag NPs doped PEDOT: PSS buffer layer was used as both buffer layer and the hole transport layer in the OLEDs devices with CBP: 45 wt% BUBD-1 blend films as the emission layer. At the optimal volume ratio of PEDOT: PSS to Ag NPs, the maximum brightness increased more than 2 times to 7823 cd/m2, and the maximum EQE increased nearly 2 times to 2.81%. The improved ASE performance of CBP: 45 wt%BUBD-1 blend films and optoelectronic properties of corresponding OLED devices can be attributed to both the localized surface plasmon resonance (LSPR) effect and the increased hole mobility caused by the addition of Ag NPs. The introduction of Ag NPs to the hole transfer layer of OLED devices may provide a potential method to realize the electrically pumped OSLs with the planar structures.

Mixing Dion–Jacobson and Ruddlesden–Popper Structures in Quasi‐2D Perovskite Films for Thermal‐ and Photo‐Stable Stimulated Emission

AbstractQuasi‐two–dimensional (2D) perovskite films are promising candidates as a gain medium for stimulated emission owing to their hydrophobicity and efficient energy funneling that facilitates the population inversion. However, the commonly used Ruddlesden–Popper (R–P) perovskites still suffer from instability induced by high‐density pumping as well as the resulting heating effect. Here, quasi‐2D perovskite films with mixed Dion–Jacobson (D–J) and R–P phases are demonstrated with both excellent amplified spontaneous emission (ASE) properties and thermal‐ and photo‐stabilities under ambient conditions. In these films, octyl ammonium bulky organic cations are used to obtain the preferred crystal orientation and highly smooth surface for low‐threshold ASE, while 1,8‐octanedi ammonium cations contribute to the greatly improved stability. The films containing the D–J phase exhibit good structural stability even after 130 °C heat treatment for 48 h. The mixed‐ligands film maintains a low ASE threshold of 11.6 µJ cm−2 and a high optical gain of 413 cm−1 after environmental annealing. It is demonstrated that it is the diammonium that firmly bonds to the perovskite layer,allowing the maintenance of quasi‐2D perovskite structure and good ASE performances.

Air-sensitive amplified spontaneous emission in lecithin-capped CsPbBr3 nanocrystals thin films

Fully inorganic lead halide perovskite nanocrystals (NCs) are receiving great attention as active materials for photonic and optoelectronic devices. While the lack of long-term stability, due to their sensitivity to ambient air exposure, currently prevents their application to commercial devices, the presence of reversible environmental effects opens the way for possible applications of lead halide perovskites in resistive or optical sensors. In this work we investigate the Amplified Spontaneous Emission (ASE) properties and their dependence on the surrounding environment of lecithin-capped CsPbBr3 NCs thin films. We demonstrate low ASE threshold under nanosecond pumping, both in air and in vacuum, with emission intensity lower in air than in vacuum. We also show that the emission quenching induced by ambient air exposure, ascribed to moisture-induced surface solvation, is reversible and it is fully restored by a suited vacuum stint application. The ASE sensitivity is up to 6.5 larger than the spontaneous emission one, making lecithin-capped CsPbBr3 NCs thin films promising systems for the development of optical humidity sensors with high sensitivity.

Aprotic Solvent Effect in Preparation of Organo Lead Iodide Perovskite Nanowires by Two-Step Spin-Coating Procedure

Lead-iodide perovskite (CH3NH3PbI3 ≡ MAPbI3) nanowires (NWs) were prepared by a two-step spin-coating technique by modifying one of the perovskite precursors with a small amount of aprotic solvent. In the two-step spin-coating technique, the perovskite precursors are MAI and PbI2. The first MAI powder is dissolved in isopropanol (IPA) to produce an isopropanol-MAI solution, while the second PbI2 is used in N, N-dimethylformamide (DMF) as an aprotic solvent. Here, a small amount of DMF was used with an IPA solution of MAI to grow 1D NWs based on MAPbI3 perovskite. Then, the film was formed directly from the MAPbI3 perovskite nanowires (PNWs) by coating the PbI2 layer with an IPA solution of MAI modified by DMF. The amount of DMF in the MAI/IPA solution was adjusted in the range between 0 and 50 μl. One-dimensional (1D) PNWs (∼100 nm diameter) and three-dimensional (3D) perovskite nanocrystals are compared. The structural and optical properties of the PNWs films are systematically investigated using X-ray diffraction patterns (XRD), scanning electron microscopy images (SEM), UV–vis absorption, and photoluminescence (PL). The result is that the presence of an additional solvent and its optimized amount in the MAI/IPA solution can increase the length and efficiency of charge transfer by facilitating perovskite transformation, as evidenced by the intensity of PL and the formation of a high-quality perovskite film. Compact, hole-free films with low trap states (crystal defects) were obtained. Further investigation of the lead iodide perovskite showed that reducing the dimensionality from 3D to 1D resulted in shorter wavelengths of the absorption edge and the PL peak in both the absorption and PL spectra. The shorter wavelengths indicate more localized exciton states in NWs. Finally, the amplified spontaneous emission (ASE) properties were obtained under picosecond laser excitation and a low ASE threshold was found at 10 and 53 μJ/cm2 for 1D and 3D, respectively, at about 300 nm film thickness.

Tailoring D-π-A architectures with hybridized local and charge transfer fluorophores exhibiting high electroluminescence exciton utilization and low threshold amplified spontaneous emission.

Novel amorphous compounds which could simultaneously use 25% singlet excitons and 75% triplet excitons as the energy source for light amplification enable the reduction of the threshold current density for electrically pumped organic semiconductor laser diodes (OSLDs); however, there is always a trade-off between the high radiative decay rate of the local excited (LE) state that is required for amplified spontaneous emission (ASE) and high exciton utilization benefiting from the charge-transfer (CT) state during electroluminescence (EL). Herein, we have explored a delicate balance to achieve both low ASE threshold and high EL exciton utilization by adopting a carefully tailored hybridized local and charge-transfer (HLCT) molecular design. A series of donor-π-acceptor (D-π-A) molecules (SBz-1, SBz-2 and SBz-3) are synthesized, and the structural change mainly refers to the spatial distance between D and A which could regulate the excited-state character via adjusting the CT length. Notably, the ASE phenomenon with a low threshold (2.97 μJ cm-2) and a high exciton utilization of 57.6% are achieved at the same time for SBz-2 with an appropriate CT length. The results provide guidance for molecular design toward harvesting triplet excitons in organic laser materials.

Optical Properties of Perovskite-Organic Multiple Quantum Wells.

A comprehensive study of the optical properties of CsPbBr3 perovskite multiple quantum wells (MQW) with organic barrier layers is presented. Quantum confinement is observed by a blue‐shift in absorption and emission spectra with decreasing well width and agrees well with simulations of the confinement energies. A large increase of emission intensity with thinner layers is observed, with a photoluminescence quantum yield up to 32 times higher than that of bulk layers. Amplified spontaneous emission (ASE) measurements show very low thresholds down to 7.3 µJ cm−2 for a perovskite thickness of 8.7 nm, significantly lower than previously observed for CsPbBr3 thin‐films. With their increased photoluminescence efficiency and low ASE thresholds, MQW structures with CsPbBr3 are excellent candidates for high‐efficiency perovskite‐based LEDs and lasers.

Amplified Spontaneous Emission Threshold Dependence on Determination Method in Dye-Doped Polymer and Lead Halide Perovskite Waveguides.

Nowadays, the search for novel active materials for laser devices is proceeding faster and faster thanks to the development of innovative materials able to combine excellent stimulated emission properties with low-cost synthesis and processing techniques. In this context, amplified spontaneous emission (ASE) properties are typically investigated to characterize the potentiality of a novel material for lasers, and a low ASE threshold is used as the key parameter to select the best candidate. However, several different methods are currently used to define the ASE threshold, hindering meaningful comparisons among various materials. In this work, we quantitatively investigate the ASE threshold dependence on the method used to determine it in thin films of dye-polymer blends and lead halide perovskites. We observe a systematic ASE threshold dependence on the method for all the different tested materials, and demonstrate that the best method choice depends on the kind of information one wants to extract. In particular, the methods that provide the lowest ASE threshold values are able to detect the excitation regime of early-stage ASE, whereas methods that are mostly spread in the literature return higher thresholds, detecting the excitation regime in which ASE becomes the dominant process in the sample emission. Finally, we propose a standard procedure to properly characterize the ASE threshold, in order to allow comparisons between different materials.

Enhanced lasing properties of BUBD-1 film with multifunctional buffer layers doped with silver nanoparticles.

The organic semiconductor lasers (OSLs) have been seen as a promising light source for future applications. Achieving organic semiconductors with low amplified spontaneous emission (ASE) threshold is a key progress toward the electrically pumped OSLs. In this paper, the ASE properties of CBP: 2wt% BUBD-1 blend films were optimized using buffer layers containing silver nanoparticles (Ag NPs) with different ratios. Both photoluminescence intensity and ASE properties of blend films were optimized when the buffer layer with 25 vol% Ag NPs was introduced. The lowest ASE threshold is 0.47 µJ/Pulse (6.71 µJ/cm2), which reduces 67.6%, and the highest gain factor is 20.14 cm-1, which enhances 47.8% compared with that without buffer layers. The enhancement of ASE properties of blend films was ascribed to the four functions of the Ag NPs doped buffer layers, including the low refractive index of PMMA and the triple localized surface plasmon resonance (LSPR) effects of Ag NPs in buffer layers. The results show that the buffer layer modified by metal nanoparticles has great application potential in improving the lasing performance of organic small molecules.

Amplified spontaneous emission of perovskite in water: Towards under-water lasing

The application of halide perovskite materials as lasing devices has recently attracted great attention. However, the instability of such materials against moisture significantly restrict the application in many occasions. In order to protect the unstable perovskite materials against oxygen and moisture, various encapsulation strategies have been proposed. Regrettably, few of them are designed for aqueous environments. Herein, we demonstrate a photo-polymerized acrylic acid (ADCP) acting as substrate and encapsulation layer to fabricate (CH3NH3)PbBr3 (MAPbBr3) films and realize amplified spontaneous emission (ASE) with low threshold in water. Lasing threshold from MAPbBr3 films sandwiched by ADCP decreases slightly from 12 μJ/cm2 in air to ∼9 μJ/cm2 in water. The specific morphology, superb wettability and high-water stability are expected to contribute to the low ASE threshold. The aqueous environment with higher refractive index is speculated to be one of the origins of the slightly lower ASE threshold. Our results demonstrate a strong potential for applications of perovskite materials in lasing devices in aqueous environment and a new path to realize low threshold lasing.

Ultrastable Gd3+ doped CsPbCl1.5Br1.5 nanocrystals blue glass for regulated and low thresholds amplified spontaneous emission

Here, Gd-doped CsPbCl 1.5 Br 1.5 nanocrystals (NCs) in borosilicate glass matrix ( B 2 O 3 − SiO 2 − ZnO ) were prepared by melting quenching and in-situ crystallization. The optical performance of CsPbCl 1.5 Br 1.5 NCs glasses under different heat-treatment temperatures and the content of Gd 3 + were analyzed in detail. After CsPbCl 1.5 Br 1.5 NCs glass is doped with Gd 3 + ions, the photoluminescence intensity increases and the synthesized Gd-doped CsPbCl 1.5 Br 1.5 NCs glasses have excellent water stability and thermal cycling performance. In addition, the influence of Gd-doped concentrations and heat-treatment temperatures on the amplified spontaneous emission (ASE) thresholds of CsPbCl 1.5 Br 1.5 NCs glasses was studied, and the Gd-doped CsPbCl 1.5 Br 1.5 NCs glasses achieve controllable ASE thresholds at room temperature. The ASE threshold can be as low as 0.39 mJ / cm 2 . This work offers a neoteric reference for the research in the application of metal ion-doped perovskite NCs and a new idea for the realization of controllable and low ASE thresholds on perovskite NCs.

Light Amplification and Efficient Electroluminescence from a Solution‐Processable Diketopyrrolopyrrole Derivative via Triplet‐to‐Singlet Upconversion

AbstractOver the years, achieving efficient electroluminescence (EL) while simultaneously having low light amplification thresholds under optical excitation has been the key to progression toward the long‐thought objective of electrically pumped organic lasers. While significant progress in this regard has been made for organic semiconductors emitting in the blue–green region of the visible spectrum, organic laser dyes with low‐energy emission (>600 nm) still suffer from high amplified spontaneous emission (ASE) thresholds and low external quantum efficiencies (EQEs) in devices. Herein, low ASE thresholds and efficient EL are reported from a solution‐processable organic laser dye dithiophenyl diketopyrrolopyrrole (DT‐DPP). The ASE threshold of 4 µJ cm−2 at the wavelength of 620 nm is obtained while making constructive use of triplet excitons by doping DT‐DPP in a green‐emitting host matrix, which exhibits thermally activated delayed fluorescence (TADF). The organic light‐emitting diode fabricated from this system gives a high EQE of 7.9% due to the efficient utilization of triplet excitons. Transient EL studies further show that a high reverse intersystem crossing rate is crucial in achieving lasing under electrical pumping from such TADF‐assisted fluorescent systems.

Deep‐Red Lasing and Amplified Spontaneous Emission from Nature Inspired Bay‐Annulated Indigo Derivatives

AbstractWhile noteworthy progress has been made on organic solid‐state lasers with low amplified spontaneous emission (ASE) thresholds and high optical gains in blue and green colors, the same advancement has not been achieved for red laser dyes. This is mainly due to their low photoluminescence quantum yields (PLQYs) because of “energy bandgap law.” Here, a new family of solution‐processable organic semiconductor laser dyes based on a bay‐annulated indigo derivative (Cibalackrot) with deep‐red emission is reported. They exhibit excellent PLQYs and low ASE thresholds (9.6 µJ cm−2) with deep‐red emission when blended in a mixed host of 1,3‐bis(N‐carbazolyl)benzene (mCP) and 2‐hydroxyphenylbenzothiazole (HBT). In contrast to a single blend in mCP, the co‐blend films are found to significantly enhance the photostability by retaining 90% of initial ASE intensity even after continuous pumping with over 9000 pulses at a pump input energy twice that of the ASE threshold, which can be attributed to efficient cascade energy transfer from mCP to HBT and then to the Cibalackrot chromophore. Low lasing threshold of 6 µJ cm−2 is further achieved at 641 nm by using distributed feedback gratings. Transient absorption spectroscopy measurements indicate that the dye has extremely low yield of triplet excited‐state under optical excitation. The results show Cibalackrot derivatives to be a promising new family of organic deep‐red laser dyes.

Low-Threshold Non-Doped Deep Blue Lasing from Monodisperse Truxene-Cored Conjugated Starbursts with High Photostability.

Herein, the photophysical, morphological, optical gain characteristics of a set of trigonal monodisperse starburst conjugated macromolecules (Tr1-Tr4) have been systematically investigated in order to elucidate the influence of the molecular structures on their optoelectronic performance. With increasing the oligofluorene arm length, absorption spectra were red-shifted progressively, whereas an increase in photoluminescence quantum yields (PLQYs) and optical gain coefficients, and a corresponding reduction in amplified spontaneous emission (ASE) thresholds and loss coefficients were observed for Tr1-Tr3 except for Tr4. The results indicate that the effective conjugation length become saturated for Tr3 in this system. Impressively, the resulting molecules manifested very low ASE thresholds (4.4-11.6 μJ cm-2 ) with high photostability, as well as high thermal stability. One dimensional distributed feedback (DFB) lasers exhibited a minimum lasing threshold of 10.38 nJ pulse-1 (0.86 kW cm-2 , 4.325 μJ cm-2 ) for Tr3. It should be emphasized that the ASE threshold of Tr1-Tr4 was nearly unchanged from room temperature to 200 °C. The results suggest that this kind of truxene-cored conjugated starbursts with high photostability and low lasing thresholds are rather promising gain media for organic semiconductor lasers.

Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MeH-PPV) Amplified Spontaneous Emission Optimization in Poly(9,9-dioctylfluorene(PFO):MeH-PPV Active Blends

In this paper we quantitatively investigate the effect of blending in an active polymer host on the Amplified Spontaneous Emission (ASE) properties of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MeH-PPV). In particular we investigate the ASE dependence of polymer:polymer blends of poly(9,9-dioctylfluorene) (PFO) and (MeH-PPV) on the blend composition. We show that ASE from the 0–1, 0-0 and even dual band is observed in the sample with a relative MeH-PPV content of 10% and that the lowest ASE threshold and the strongest ASE intensity increase with the excitation density are obtained for a MeH-PPV relative content of 25% in weight, with a threshold decrease of 26 times with respect to neat MeH-PPV films. These effects are ascribed to the interplay between the increase of Förster Resonant Energy Transfer from PFO to MeH-PPV dominating up to a MeH-PPV content of 25% and the increase of MeH-PPV aggregation, dominating at higher values of the MeH-PPV content. We also demonstrate that the blend content affects the local emission properties due to variations of the uniformity of the MeH-PPV distribution within the PFO matrix, of MeH-PPV clustering and aggregation. Beyond improving the understanding of the PFO:MeH-PPV interaction in active blends our results can be exploited for the optimization of organic optically pumped lasers based on active polymer:polymer blends.

Low Amplified Spontaneous Emission Threshold and Efficient Electroluminescence from a Carbazole Derivatized Excited-State Intramolecular Proton Transfer Dye

The search for new classes of efficient electroluminescent organic laser dyes with low amplified spontaneous emission (ASE) threshold (Eth) and low optical losses is crucial toward the realization of organic injection lasers. In this work, we report in-depth studies of an organic semiconducting laser dye, benzo[d]thiazol-2-yl)-5-(9H-carbazol-9-yl)phenol (HBT-Cz), and compare the photophysical study with its parent HBT dye. While HBT is not laser-active in solution, the carbazole derivatized dye (i.e., HBT-Cz) showed a low solution ASE threshold of 21 mJ/cm2, which is comparable to a common high-performing commercial laser dye, Rhodamine 6G (Rh-6G). HBT-Cz also exhibited a low film ASE threshold of 2.4 μJ/cm2 with a low optical loss coefficient of 1.5 cm–1, which is the lowest waveguide loss coefficient reported for solution-processed organic semiconductors. Organic light-emitting diodes based on this material showed a high maximum EQE of 1.9%, which is close to the theoretical EQE limit of the emitter, an...

Enhancing Optical Gain Stability for a Deep-Blue Emitter Enabled by a Low-Loss Transparent Matrix

Efficient organic gain media with high optical gain and good photostability are highly desirable for organic semiconductor lasers. To shed light on the rational molecular design, in this work, a novel deep-blue organic emitter consisting of a carbazole core substituted by a diphenylamine-functionalized triazine unit and two arms of bifluorene with flexible alkyl chains (denoted as C2) was designed and synthesized. Various basic photophysics and amplified spontaneous emission (ASE) characterizations were conducted with a particular focus to unravel the impact of the molecular structure on the photostability. Relatively low ASE threshold of 7.0 μJ/cm2, high net gain coefficient of 79.9 cm–1 (under 40-fold threshold pump fluence), and low optical loss coefficient of 7.0 cm–1 were recorded for C2 in neat films. For comparison, C2 was also dispersed into polystyrene (PS), a low-loss transparent matrix, with various ratios to form PS-C2 blend films. Among them, a 50 wt % PS-C2 blend film exhibited a high gain c...

Preferential Orientation of Crystals Induced by Incorporation of Organic Ligands in Mixed‐Dimensional Hybrid Perovskite Films

AbstractOrganic–inorganic perovskites demonstrate great potential for optical applications due to their intriguing optical and optoelectronic properties. Dedicated efforts have been carried out to understand the energy landscape and charge carrier mobilities for perovskite materials. In order to further boost these materials toward large‐scale applications, an alternative “bottom‐up” route for the understanding about correlation between the morphology of high‐quality planar films and their optical properties is essential. Here, mixed‐dimensional bromide‐based hybrid perovskite thin films are prepared from a simple one‐step solution processing route using mixtures of methylammonium bromide (MABr) and octylammonium bromide (OABr). Grazing incidence scattering data statistically reveal that the development of thin‐film morphology as well as crystal orientation depends on the orientation of the OABr crystallites. This study opens up further insight into the morphology of perovskite thin films. In combination, the occurrence of amplified spontaneous emission (ASE) in perovskite films with low ASE thresholds with values approaching 17.8 µJ cm−2 is demonstrated and appears to be closely correlated to the tailored morphology, highlighting its importance for realizing optical gain media.