ACS Applied Optical Materials最新文献

{"title":"Nanocomposite Garnet-Enabled Monolithically Integrated Magneto-Optical Isolator Using an Asymmetric Mach–Zehnder Interferometer","authors":"Tomoya Sugita,&nbsp;Hibiki Miyashita,&nbsp;Reona Motoji,&nbsp;Dan Maeda,&nbsp;Hiroki Yamamoto,&nbsp;Yuki Yoshihara,&nbsp;Kazushi Ishiyama,&nbsp;Taichi Goto","doi":"10.1021/acsaom.6c00176","DOIUrl":"10.1021/acsaom.6c00176","url":null,"abstract":"<p>Monolithically integratedmagneto-optical (MO) isolators are crucialfor photonic integrated circuits. We demonstrate an isolator basedon an asymmetric Mach–Zehnder interferometer with 4.4 dB MO-loadinginsertion loss and an 18.7 dB isolation ratio at wavelengths between1550 and 1570 nm, using a nanocomposite garnet film that achievesboth large Faraday rotation and compatibility with silicon substrates.The garnet composite consists of ∼10 nm cerium-rich segregationsin a single-crystalline cerium-substituted yttrium iron garnet (Ce:YIG)matrix with 1–5 μm-scale grains on silicon substrates.These results demonstrate the effectiveness of nanocomposite garnetfilms prepared by gradual annealing for realizing integrated magneto-opticalisolators. The nanocomposite garnet film exhibited a Faraday rotationof −0.25°/μm, an optical absorption of −4.9dB/cm, and an MO figure of merit of 510°/dB, four times greaterthan that of our previously reported polycrystalline Ce:YIG film.</p>","PeriodicalId":29803,"journal":{"name":"ACS Applied Optical Materials","volume":"4 6","pages":"1813–1820"},"PeriodicalIF":3.4,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148624697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design of Luminescent LDH–Polymer Hybrids via Thermally Activated Molecular Pillaring as an Antimigration Strategy for Fluorophores in Polymers","authors":"Guillaume Zerbib,&nbsp;Damien Boyer,&nbsp;Geneviève Chadeyron,&nbsp;Fabrice Leroux","doi":"10.1021/acsaom.6c00121","DOIUrl":"https://doi.org/10.1021/acsaom.6c00121","url":null,"abstract":"<p>In the approach involving the coinsertion of opticallyactive moleculesand molecular spacers, only very small amounts of fluorophores areused. These fluorophores must be both well dispersed as well as immobilizedto prevent the “aggregation-caused quenching” (ACQ)phenomenon and to ensure efficient and durable optical emission. Theinorganic framework of layered double hydroxide (LDH) is known tooffer favorable conditions for such requirements. In this study, thermallylinkable spacers are used to close the interlayer space of the LDHhost, forming a pillared structure that effectively prevents the migrationof organic fluorophores out of the host layers. By using vinylbenzenesulfonate(VBS) or sulfopropyl methacrylate (SPMA), optimal external photoluminescencequantum yields (PLQY_ext) are achieved with sulforhodamineB (SRB), even at relative loadings as low as 0.01 mol % and 0.03 mol% of LDH’s anion exchange capacity. For practical applications,such as in optics, the luminescent LDH powders are dispersed withina polymer matrix, where a major challenge lies in preventing fluorophoremigration. The confinement provided by the present system is remarkable,as no trace of fluorophore was detected even under harsh acceleratedmigration tests.</p>","PeriodicalId":29803,"journal":{"name":"ACS Applied Optical Materials","volume":"4 6","pages":"1728–1740"},"PeriodicalIF":3.4,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148651002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"4-Tritylphenyl-Grafted Carbon Nitride: Facile Synthesis via Deamination Thermal Polymerization and Its Application in LEDs","authors":"Aijing Jiang,&nbsp;Jinghao Zhang,&nbsp;Huaijun Tang,&nbsp;Xiang Li,&nbsp;Zhouyang Jiang,&nbsp;Xiuying Fang,&nbsp;Rongman Xia,&nbsp;Weixian Wang,&nbsp;Yifei Li,&nbsp;Yibing Wu,&nbsp;Qiang Zhou,&nbsp;Zhengliang Wang","doi":"10.1021/acsaom.6c00137","DOIUrl":"10.1021/acsaom.6c00137","url":null,"abstract":"<p>Rare-earth-free luminescent materials, including carbonnitride(C₃N₄) derivatives, are becoming a new researchhotspot. Herein, a 4-tritylphenyl-grafted C₃N₄ derivative (C₃N₄-TTP) is synthesized usingdicyandiamide as the main precursor and 4-tritylaniline as the dopingprecursor via deamination thermal polymerization. The optimal synthesisconditions for C₃N₄-TTP are a molar ratio ofdicyandiamide to 4-tritylaniline of 15:1 at 450 °C for 1.5 h.In C₃N₄-TTP, donor–acceptor bipolar structuralunits are formed by the electron-donating 4-tritylphenyl moietiesand the electron-withdrawing heptazines. Mainly due to the modification,compared with bulk g-C₃N₄, the photoluminescencequantum yield increases from ∼5.0% to 25.4% and the emissioncolor shifts from blue to yellow-green. C₃N₄-TTP has high thermal stability up to 450 °C, and it retains69.2% of the relative maximum emission intensity at 150 °C comparedwith that at 30 °C, suggesting its good potential for applicationsin light-emitting diodes (LEDs). Excited by GaN-based blue-light chips(460 nm, 25.0 lm·W^–1), C₃N₄-TTP can be used not only as a single phosphor to fabricate yellow-greenLEDs but also combined with red phosphor K₂SiF₆:Mn⁴⁺ to construct high-performance white LEDs. The bestwhite LED exhibits a high color rendering index of 89.2, a suitablecorrelated color temperature of 6343 K, a luminous efficiency of 28.24lm·W^–1, and a CIE chromaticity coordinate of(0.31, 0.37).</p>","PeriodicalId":29803,"journal":{"name":"ACS Applied Optical Materials","volume":"4 6","pages":"1741–1752"},"PeriodicalIF":3.4,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148624692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polymorph-Dependent Photophysics of Blue-Emitting Brominated Organic Crystals","authors":"Haydee Pacheco,&nbsp;Jesus Valdiviezo,&nbsp;Rianne G. De Leon,&nbsp;Thomas J. Emge,&nbsp;Mircea Cotlet,&nbsp;Deirdre M. O’Carroll","doi":"10.1021/acsaom.6c00105","DOIUrl":"10.1021/acsaom.6c00105","url":null,"abstract":"<p>Nonmetal-containing organic molecules typically do notemit bluephosphorescence efficiently due to weak intersystem crossing and thechallenge of protecting high-energy triplet states from nonradiativedecay. We show that use of triplet-promoting bromine atoms and carefulcontrol of molecular packing can lead to well-defined, efficient room-temperaturephosphorescence (RTP) from organic crystals. We report on the distinctoptical properties of a polymorphic bromine-containing organic molecule,1,4-bis(bromomethyl)-2,5-bis(octyloxy)benzene (Br8) in solid-state(micro)crystal and thin-film forms. The two polymorphs, named Br8-Hand Br8-J, exhibit different molecular packing arrangements in singlecrystals and thin films and, consequently, different photophysicalbehaviors. The Br8-J polymorph is characterized by a head-to-tailmolecular arrangement in a triclinic crystal, while the Br8-H polymorphadopts a face-to-face arrangement (monoclinic crystal). Br8-J hasa higher quantum yield (38% for the microcrystal form and 8% for thethin film), lower energy, and narrower emission, compared to Br8-H(quantum yield of just 2% for the microcrystal and 0.2% in the thinfilm). The higher quantum yields in the microcrystal forms indicatethe key role of intermolecular interactions in reducing nonradiativerecombination in these polymorphs. The presence of both prompt anddelayed blue emission (in the range 420–470 nm) and large Stokesshifts from both polymorphs indicates the involvement of triplet excitedstates and the occurrence of RTP with lifetimes of ∼325 μs.With an emission wavelength of 470 nm and a quantum yield of 38%,the Br8-J polymorph demonstrates how specific head-to-tail packingcan unlock highly efficient solid-state phosphorescence compared toits face-to-face counterpart. The optimal intermolecular halide bondingin the J-type packing arrangement combined with the heavy atom effectis key to unlocking efficient blue emission from Br8 crystals. Ourfindings uncover rich photophysics in halogenated organic moleculesin the solid state and the importance of molecular packing in theiremission characteristics.</p>","PeriodicalId":29803,"journal":{"name":"ACS Applied Optical Materials","volume":"4 6","pages":"1689–1698"},"PeriodicalIF":3.4,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148362563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrical and Optical Characteristics of 395 nm InGaN-Based Ultraviolet-A Micro-Light Emitting Diodes with Different Sidewall Passivation Methods","authors":"Kijun Kwon,&nbsp;Byeong-U Bak,&nbsp;Youngwook Shin,&nbsp;Jaekyun Kim","doi":"10.1021/acsaom.6c00111","DOIUrl":"10.1021/acsaom.6c00111","url":null,"abstract":"<p>This study examines the impact of different sidewallpassivationmethods on the electrical and optical characteristics of 395 nm ultraviolet-A(UV-A) microlight-emitting diodes (μLEDs). Silicon dioxide depositedby plasma-enhanced chemical vapor deposition, aluminum oxide depositedby plasma-enhanced atomic layer deposition, and aluminum oxide depositedby thermal atomic layer deposition (thermal ALD) were compared asrepresentative sidewall passivation methods. All devices were fabricatedon the same epitaxial wafer through an identical top-down processflow, with mesa sizes ranging from 30 to 100 μm. Differenceswere observed in current–voltage behavior, ideality factor,surface and bulk current components, light output power, and externalquantum efficiency. Among the three passivation conditions, the thermalALD Al₂O₃ devices showed lower leakage current,lower ideality factor, a smaller surface-current contribution, andsmaller optical degradation as the device size decreased. These resultsprovide a comparative data set for discussing sidewall-related behaviorin UV-A μLEDs.</p>","PeriodicalId":29803,"journal":{"name":"ACS Applied Optical Materials","volume":"4 6","pages":"1719–1727"},"PeriodicalIF":3.4,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148672570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From Astrophysics to Perovskites: Why Saha Physics Cannot Describe the Exciton to Free Electron–Hole Pairs Statistics in Semiconductors","authors":"Giuseppe Ammirati,&nbsp;Faustino Martelli,&nbsp;Daniele Catone,&nbsp;Patrick O’Keeffe,&nbsp;Stefano Turchini","doi":"10.1021/acsaom.6c00127","DOIUrl":"10.1021/acsaom.6c00127","url":null,"abstract":"<p>The Saha equationhas long served as the standard modelfor describingthermodynamic equilibrium between neutral atoms and their ionizedcounterparts in astrophysical plasmas. Over the past decade, thisformalism has been increasingly adopted to describe the equilibriumbetween excitonic and free electron–hole (e–h) populationsin semiconductors, especially halide perovskites. Here, we argue thatthis application is fundamentally limited. The Saha equation has beendeveloped for systems in thermodynamic equilibrium, while a photoexcitedsemiconductor is out of equilibrium. Moreover, in all semiconductors,strong many-body interactions, density-dependent Coulomb screening,and band gap renormalization invalidate the key Saha assumption ofa fixed exciton binding energy. As a result, Saha-based phase diagramsfail to capture the Mott transition, the density-driven transitionfrom an excitonic gas to a plasma of free electron–hole pairs,and to describe semiconductor laser operation. We hope that our considerationshelp the perovskite community correctly describe the electronic populationin their works.</p>","PeriodicalId":29803,"journal":{"name":"ACS Applied Optical Materials","volume":"4 6","pages":"1546–1549"},"PeriodicalIF":3.4,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148362568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stepwise Molecular Confinement Enabling Persistent Room-Temperature Phosphorescence in Blue Graphene Quantum Dots with Quantum Yield Exceeding 60%","authors":"Adila Rani,&nbsp;Jaemin Jeong,&nbsp;Sangwoo Park,&nbsp;Kyusang Cho,&nbsp;Gunsu Yun,&nbsp;Soo Young Kim,&nbsp;Seokwoo Jeon","doi":"10.1021/acsaom.6c00210","DOIUrl":"10.1021/acsaom.6c00210","url":null,"abstract":"<p>Graphenequantum dots (GQDs) face major challenges in solid-stateluminescent applications due to aggregation-induced quenching, surfacedefects, and dominant nonradiative decay pathways. In this study,a stepwise molecular hybridization strategy was developed to simultaneouslyenhance solution fluorescence and solid-state room-temperature phosphorescence(RTP) of GQDs. GQDA (graphene quantum dot–APTES) introducessiloxane-related hybridization through Si–O–Si and possibleSi–O–C interactions, while UGQD (urea–GQD) providesnitrogen-related surface passivation and hydrogen-bond-assisted confinement.The fully hybridized UGQDA system combines both structural rigidificationand molecular passivation within a cooperative hybrid framework. Asa result, UGQDA exhibits bright fluorescence in solution togetherwith persistent solid-state RTP, addressing the common limitationin carbon nanomaterials where fluorescence and phosphorescence aretypically optimized separately. The optimized UGQDA hybrid achievesa photoluminescence quantum yield (PLQY) of approximately 60% at 2.0wt % GQD loading, compared with 3.2% for pristine GQDs, together withenhanced photoluminescence intensity in both solution and solid states.The hybrid system additionally exhibits prolonged room-temperatureafterglow lasting up to 10 s and phosphorescence lifetimes approaching0.9 s under ambient conditions. The enhanced optical behavior is consistentwith reduced nonradiative relaxation, increased structural confinement,and progressive reduction of the singlet–triplet energy gap(Δ<em>E</em>_ST) from 0.23 eV in pristine GQDs to 0.15eV in UGQDA. These findings demonstrate that cooperative molecularhybridization provides an effective strategy for developing heavy-metal-freephosphorescent GQD materials for optical security, anticounterfeiting,and advanced luminescent applications.</p>","PeriodicalId":29803,"journal":{"name":"ACS Applied Optical Materials","volume":"4 6","pages":"1873–1884"},"PeriodicalIF":3.4,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148656294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Color-Tunable TS-FRET Regulated Dual-Mode White Emission Metal-Free Room Temperature Afterglow Materials for Information Anticounterfeiting Encryption and WLEDs","authors":"Mingrui Li,&nbsp;Kun Gong,&nbsp;Kejian Jiang,&nbsp;Bowei Wang,&nbsp;Wei Li,&nbsp;Dongzhi Liu,&nbsp;Xueqin Zhou","doi":"10.1021/acsaom.6c00255","DOIUrl":"https://doi.org/10.1021/acsaom.6c00255","url":null,"abstract":"<p>Metal-free room temperature afterglow (RTA) materialssimultaneouslyexhibiting white photoluminescence (PL) and afterglow present a challengingand significant endeavor. In this work, color-tunable (cyan, yellow,and red) RTA materials were successfully prepared by doping anthraquinone(AN), naphthalic anhydride (NA), and rhodamine B (RhB) into BA. Basedon the complementary colors of the single-component doped samples <strong>AN</strong>_{<strong>2</strong>}<strong>@BA</strong> and <strong>RhB</strong>_{<strong>2</strong>}<strong>@BA</strong>, along with TS-FRET fromNA@BA to RhB@BA, the optimal sample <strong>AN</strong>_{<strong>2</strong>}<strong>/NA</strong>_{<strong>0.6</strong>}<strong>/RhB</strong>_{<strong>3</strong>}<strong>@BA</strong> was successfully preparedby blending AN, NA, and RhB in varying ratios. This sample exhibitswhite photoluminescence (mixed cyan, blue, and red light) and whiteafterglow (mixed cyan, yellow, and red light). Its CIE coordinatesare (0.3485, 0.3186) and (0.3120, 0.3417), respectively. Moreover, <strong>AN</strong>_{<strong>2</strong>}<strong>/NA</strong>_{<strong>0.6</strong>}<strong>/RhB</strong>_{<strong>3</strong>}<strong>@BA</strong> issuccessfully applied in information encryption anticounterfeitingand white light-emitting diode (WLEDs) with a CCT of 6386 K, CIE colorcoordinates of (0.3145, 0.3327), and a CRI of 80. This research offersa promising design method for constructing metal-free RTA materialsthat can simultaneously exhibit white photoluminescence and afterglow.</p>","PeriodicalId":29803,"journal":{"name":"ACS Applied Optical Materials","volume":"4 6","pages":"1929–1938"},"PeriodicalIF":3.4,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148666584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecularly Engineered Dual-Emission Pathways with Monomer–Excimer Interplay for Single-Component Blue and White Organic Light-Emitting Diodes","authors":"Ehsan Ullah Rashid,&nbsp;Rishika Suresh,&nbsp;Dmytro Volyniuk,&nbsp;Sathiyanarayanan Kulathu Iyer,&nbsp;Juozas V. Grazulevicius","doi":"10.1021/acsaom.6c00161","DOIUrl":"10.1021/acsaom.6c00161","url":null,"abstract":"<p>The design of an organic molecule that inherently exhibitsmultipleemissive channels provides an elegant strategy for structurally simpleyet spectrally broad white organic light-emitting diodes (OLEDs).Herein, we report the rational design and synthesis of a donor−π-acceptorluminophore (<strong>DBP-PXZ</strong>), comprising a phenoxazine donormoiety and a tetrahydrodibenzophenanthridine acceptor fragmentlinked through a twisted phenylene bridge. The photoluminescence (PL)spectrum of the solid sample of the compound exhibits dual emissionbands, resulting in single-component white emission with CIE coordinatesof (0.31, 0.38). PL spectral analysis of the solid solutions in polarhost matrices and in a PMMA matrix demonstrates that controlled modulationof intermolecular proximity selectively activates or suppresses alow-energy emissive channel. Close chromophore packing activates intermolecularcharge transfer (CT)-type excimer emission, while spatial isolationsuppresses this pathway and yields purely blue emission from the monomericCT state. Computational calculations support the stabilization ofan intermolecular CT excited state of dimeric models relative to themonomeric ones. Leveraging this dual-emissive nature, host-free OLEDsbased on a thin layer of <strong>DBP-PXZ</strong> as emissive layer exhibita broadband electroluminescence spectrum spanning the range of ca.385–800 nm. The device with an emissive layer of diluted <strong>DBP-PXZ</strong> with a wide-bandgap host effectively suppresses excimerformation and enables a pure blue EL spectrum. This work highlights <strong>DBP-PXZ</strong> as a single-component emitter enabling tunable blue-to-whiteemission via monomeric and excimer CT states, offering a compositionallysimplified and heavy-metal-free emitter approach inspired by a sustainability-drivenOLED design.</p>","PeriodicalId":29803,"journal":{"name":"ACS Applied Optical Materials","volume":"4 6","pages":"1787–1797"},"PeriodicalIF":3.4,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148362601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Emulsion–Demulsion Route to MAPbI3 Perovskite Thin Films for Optical Energy Transducer Application","authors":"Adithya Nath Reghunathan,&nbsp;Aruna Raj,&nbsp;Ramakrishnan Jayakrishnan","doi":"10.1021/acsaom.6c00050","DOIUrl":"10.1021/acsaom.6c00050","url":null,"abstract":"<p>We report the synthesis of methylammonium lead iodide(MAPbI₃) thin films via an emulsion–demulsion (E-LARP)routeand provide a comprehensive evaluation of their structural, optical,and optoelectronic properties with emphasis on stability and energytransduction performance. X-ray diffraction and transmission electronmicroscopy confirm the tetragonal <em>I</em>4/<em>mcm</em> phase with nanocrystalline ordering, while elemental mapping andsurface analyses reveal intrinsic Pb–I bonding alongside pronouncedenvironmental reactivity. Pristine films exhibit a sharp absorptiononset near 770–780 nm and strong photoluminescence consistentwith a direct bandgap of ∼1.55 eV. Under ambient exposure,optical degradation is marked by hydrate-phase transitions, PbI₂ formation, and defect-state emissions, underscoring the material’ssensitivity to moisture and oxygen. Temperature-dependent photoluminescencefurther reveals a tetragonal-to-orthorhombic transition below ∼160 K,accompanied by exciton localization and phonon-coupled broadening.Device prototyping with FTO/MAPbI₃/Ag heterojunctions demonstratesdiode-like rectification, high photosensitivity (∼8.3), andmeasurable quantum efficiency, though photocurrent decay under continuousillumination reflects intrinsic photoinstability. Collectively, thesemultitechnique investigations establish the emulsion–demulsionroute as a viable pathway for MAPbI₃ thin films in optoelectronicapplications, while emphasizing the critical need for encapsulation,compositional engineering, and interface passivation to achieve long-termoperational stability.</p>","PeriodicalId":29803,"journal":{"name":"ACS Applied Optical Materials","volume":"4 6","pages":"1647–1660"},"PeriodicalIF":3.4,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148656332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}