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Abstract Among promising applications of metal‐halide perovskite, the most research progress is made for perovskite solar cells (PSCs). Data from myriads of research work enables leveraging machine learning (ML) to significantly expedite material and device optimization as well as potentially design novel configurations. This paper represents one of the first efforts in providing open‐source ML tools developed utilizing the Perovskite Database Project (PDP), the most comprehensive open‐source PSC database to date with over 43 000 entries from published literature. Three ML model architectures with short‐circuit current density (J_sc) as a target are trained exploiting the PDP. Using the XGBoost architecture, a root mean squared error (RMSE) of 3.58 , R²of 0.35 and a mean absolute percentage error (MAPE) of 9.49% are achieved. This performance is comparable to results reported in literature, and through further investigation can likely be improved. To overcome challenges with manual database creation, an open‐source data cleaning pipeline is created for PDP data. Through the creation of these tools, which have been published on GitHub, this research aims to make ML available to aid the design for PSC while showing the already promising performance achieved. The tools can be adapted for other applications, such as perovskite light‐emitting diodes (PeLEDs), if a sufficient database is available. 

Abstract This study presents the Br‐rich in situ synthesis of blue‐emitting 2D CsPbBr₃nanoplatelets (NPLs) with various Br/Pb ratios using ZnBr₂as a Br precursor to enhance Br ion adsorption significantly. This leads to effective passivation of surface defects, particularly Pb−Br bonds, by increasing the positive charge density around Pb atoms, thus creating a stable bonding environment and reducing defect formation. Consequently, the photoluminescence quantum yield (PLQY) improves from 31.15% for a Br/Pb ratio of 2 to 87.2% for a ratio of 6. NPLs with a Br/Pb ratio of 6 also exhibit longer lifetimes (16.69 ns) and slower bleach recovery dynamics, indicating fewer non‐radiative recombination pathways and effective exciton dynamics. Additionally, NPLs with the Br/Pb ratio of 6 demonstrated better thermal stability, with an activation energy of 124.3 meV, indicating stronger exciton binding. These NPLs also exhibited enhanced stability, with UV tolerance at 43.9% and water resistance at 23.8%, making them suitable for displays and lighting. Furthermore, Br‐passivated CsPbBr₃NPLs are used as blue emitters in prototype white LEDs, achieving a wide color gamut, 126.6% of the National Television Standards Committee and 94.5% of Rec. 2020, demonstrating their potential for high‐quality lighting and advanced display technologies. 

Metal halide perovskite light-emitting diodes (PeLEDs) have experienced a rapid advancement in the last several years with the external quantum efficiencies (EQEs) reaching over 20%, comparable to the state-of-the-art organic LEDs and quantum dot LEDs. The photoluminescence quantum yields of perovskite films have also been approaching 100%. Therefore, the next step to improving the EQE of PeLEDs should be focused on boosting light extraction. In this Letter, we demonstrate the emitter dipole orientation as a key parameter in determining the outcoupling efficiency of PeLEDs. We find that the ${\mathrm{C}\mathrm{s}\mathrm{P}\mathrm{b}\mathrm{B}\mathrm{r}}_3$emitter has a slightly preferred orientation with the horizontal-to-vertical dipole ratio of 0.41:0.59, as compared to 0.33:0.67 in the isotropic case. A theoretical analysis predicts that a purely anisotropic perovskite emitter may result in a maximum EQE of 36%. 

A green‐emitting perovskite first‐order distributed feedback (DFB) laser based on the methylammonium lead bromide (MAPbBr₃) with high stability is demonstrated for the first time. The laser achieves stable lasing at 550 nm with a full width at half maximum of 0.4 nm. Low lasing threshold of 60 μJ cm⁻²under nanosecond pulsed excitation and 3.1 μJ cm⁻²under femtosecond pulsed excitation is observed, showing a much lower lasing threshold compared with the second‐order DFB cavities, which are fabricated on the same substrate. By optimizing the antisolvent treatment and encapsulating with poly(methyl methacrylate), the laser lifetime, resistance to moisture, lasing threshold, and intensity are significantly improved. The lasers are fabricated with a complementary metal‐oxide‐semiconductor‐compatible process, thus offer promising potential for the integrated photonic devices. 

Abstract The high transmission speed of optical signals and their application in optical computation have created a growing demand for photon‐programmed memory devices. Rather than using electrical pulses to store data in one of two states, the photomemory (PM) devices exploit the optical stimulation to store the light information. In this work, the application of a nonvolatile rewritable PM array using the photochromic inorganic perovskite CsPbIBr₂grown by a vapor‐deposition process is demonstrated. Reversible phase transitions between orthorhombic (δ) and cubic (α) phases are achieved in CsPbIBr₂films through laser‐induced heat and moisture exposure. The PM pixels in an optically absorbing perovskite phase exhibit ≈50‐fold photoresponsivity as large as those in a transparent‐colored non‐perovskite phase. Storing optical data are achieved by heating pixels through a near‐infrared laser, while moisture exposure is used to erase the stored information. The nonvolatile PM array exhibits great write‐read‐erase cycle endurance and data retention capability without obvious performance degradation after storage in air for one week. This work demonstrates the promising application of vapor‐deposited inorganic perovskite for optical information storage and the unique potential of them for use in optical switches, tunable metasurfaces, and many other applications.