A myriad of studies and strategies have already been devoted to improving the stability of perovskite films; however, the role of the different perovskite crystal facets in stability is still unknown. Here, we reveal the underlying mechanisms of facet-dependent degradation of formamidinium lead iodide (FAPbI₃) films. We show that the (100) facet is substantially more vulnerable to moisture-induced degradation than the (111) facet. With combined experimental and theoretical studies, the degradation mechanisms are revealed; a strong water adhesion following an elongated lead-iodine (Pb-I) bond distance is observed, which leads to a δ-phase transition on the (100) facet. Through engineering, a higher surface fraction of the (111) facet can be achieved, and the (111)-dominated crystalline FAPbI₃ films show exceptional stability against moisture. Our findings elucidate unknown facet-dependent degradation mechanisms and kinetics.

A myriad of studies and strategies have already been devoted to improving the stability of perovskite films; however, the role of the different perovskite crystal facets in stability is still unknown. Here, we reveal the underlying mechanisms of facet-dependent degradation of formamidinium lead iodide (FAPbI₃) films. We show that the (100) facet is substantially more vulnerable to moisture-induced degradation than the (111) facet. With combined experimental and theoretical studies, the degradation mechanisms are revealed; a strong water adhesion following an elongated lead-iodine (Pb-I) bond distance is observed, which leads to a δ-phase transition on the (100) facet. Through engineering, a higher surface fraction of the (111) facet can be achieved, and the (111)-dominated crystalline FAPbI₃ films show exceptional stability against moisture. Our findings elucidate unknown facet-dependent degradation mechanisms and kinetics.

Abstract Hardware-based cryptography that exploits physical unclonable functions is required for the secure identification and authentication of devices in the Internet of Things. However, physical unclonable functions are typically based on anticounterfeit identifiers created from randomized microscale patterns or non-predictable fluctuations of electrical response in semiconductor devices, and the validation of an encrypted signature relies on a single-purpose method such as microscopy or electrical measurement. Here we report nanoscale physical unclonable function labels that exploit non-deterministic molecular self-assembly. The labels are created from the multilayer superpositions of metallic nanopatterns replicated from self-assembled block copolymer nanotemplates. Due to the nanoscale dimensions and diverse material options of the system, physical unclonable functions are intrinsically difficult to replicate, robust for authentication and resistant to external disturbance. Multiple, independently operating keys—which use electrical resistance, optical dichroism or Raman signals—can be generated from a single physical unclonable function, offering millisecond-level validation speeds. We also show that our physical unclonable function labels can be used on a range of different surfaces including dollar bills, human hair and microscopic bacteria.

A physically unclonable function (PUF) is a promising hardware-based cryptographic primitive to prevent confidential information leakage. However, conventional techniques, such as weak and strong PUFs, have limitations in overcoming the trade-off between security and storage volume. This study introduces nanoseed-based PUFs that overcome the drawbacks of conventional PUFs using optical and electrical randomness originated from nanoseeds and a unique on-demand cryptographic algorithm. Ideally mixed PbS quantum dots and Ag nanocrystals in the same medium are exploited as nanoseeds to simultaneously promote independent optical and electrical randomness. The number of secured keys that can be generated on-demand by combining the optical and electrical features in parallel using shuffling method is almost infinite (>10⁵⁸⁷⁴¹ per square millimeter). The proposed PUF achieves a near-ideal Hamming distance in uniqueness and randomness tests, validating its cryptographic efficacy. Last, storage-free and on-demand PUF with the shuffling method are demonstrated using smartphones, realizing manufacturer-/user-friendly cryptography system.

This work highlights the potential of RL-MPC to achieve energy-efficient performance in real-world driving scenarios without the need for full travel information. Although dynamic programming (DP) can achieve a globally optimal solution, it requires full travel information, such as the whole velocity profile. To address this limitation, we decompose the optimal control problem into stage and terminal costs, allowing optimization without full travel information. Model predictive control (MPC) is used to solve stage cost when short-term predicted information is available. In addition, terminal costs are incorporated to penalize the state using a value function. Using similar driving patterns of the repeated routes, we approximate the value function that exhibits near optimality through reinforcement learning (RL). Compared to conventional MPC, which is based solely on short-term information, RL-MPC reduces fuel consumption by 5.53% while meeting the final state of charge (SOC) condition.

Plasmonic Ternary Physical Unclonable Function In article In their Research Article (DOI: 10.1002/adma.202503976), Sunkook Kim, Dong-Hwan Kim, and co-workers report a ternary physical unclonable function that exploits the Brownian motion of nanoparticles as a robust entropy source through an optical printing approach. The cover illustrates optical printing of gold nanoparticles, where minute fluctuations induced by stochastic Brownian motion are encoded into unpredictable outcomes under deterministic optical forces.

We propose that TBST is an effective and practical buffer to preserve diluted antibodies, which can be utilized as an integral part of strategies to reduce antibody consumption in laboratories.

An on-demand fabrication method for additive physical unclonable functions (PUFs), a hardware-based security primitive, is inevitably required, especially considering increasingly miniaturized microelectronic devices. An optical printing approach is regarded as an alternative method to fabricate functional nano/microscale patterns against conventional methods due to its superior fabrication flexibility. However, owing to the Brownian motion of nanoparticles, achieving highly precise and selective printing persists an ongoing obstacle for the applicability of optical printing methods. Here, it is shown that the optical printing approach possesses plenty of room to fabricate on-demand PUFs by exploiting the obstacle from the perspective of randomness. To demonstrate this, an optical PUF based on a mesoscopic lattice pattern consisting of optically printed gold nanoparticles is proposed. Comprehensive analyses on physical features occurring naturally and multi-modal keys generated from them reveal that both exhibit randomness. Through a ternary bit system and key integration approach, the capability of the physical unclonable function using as few as 25 nanoparticles can be ensured in terms of the amount of information, complexity, uniqueness, and encoding capacity. The versatility of optical printing regarding the usability of a broad range of substrates and the ability to create arbitrary patterns with tunable dimensions are also shown.

Abstract With dramatically growing demand for highly complicated, high power‐consumed 3D stacked integrated circuit electronics, the advancement of effective thermal management has become a key technology to secure both performance and stability. To ensure better heat management of integrated microelectronics, especially pursuing unconventional devices assembled on a sheet of paper or plastics, more feasible and effective heat management is inevitable. In this study, the mechanically robust and bi‐directionally thermal conductive material are presented by micro‐molding with boron‐nitride (BN) microscale platelets (µ‐platelets) dispersed in the polymeric matrix. Micro‐pattern‐induced bifurcation of assembly orientation of the BN µ‐platelets and bi‐directionality of heat conduction characteristics are observed. The bifurcated orientations of the BN µ‐platelets are optimized by the geometry of the micro‐pattern and unit size of the platelets with the assistance of particle‐fluid simulation. Indeed, exceptionally enhanced thermal conductivities through both directions: 6.9 W m −1 K −1 in the through‐plane and 7.4 W m −1 K −1 in the in‐plane, respectively are achieved. It also exhibits flexibility with a minimum radius of curvature ≈1 mm and the capability of conformal contact to diverse morphologies to stably secure heat flow even in mechanically deformed device structures. The developed TIM can be applied to high‐power, high‐temperature, and mechanically deformable application environments of 3D‐integrated electronics.