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1. Machine learning enhanced characterization and optimization of photonic cured MAPbI ₃ for efficient perovskite solar cells

   https://doi.org/10.20517/jmi.2024.72  

   Allen, Cody R; Bhandari, Bishal; Xu, Weijie; Lee, Mark; Hsu, Julia_W P (December 2024, Journal of Materials Informatics)

   Photonic curing (PC) can facilitate high-speed perovskite solar cell (PSC) manufacturing because it uses high-intensity light pulses to crystallize perovskite films in milliseconds. However, optimizing PC conditions is challenging due to its many variables, and using power conversion efficiency (PCE) as the optimization metric is both time-consuming and labor-intensive. This work presents a machine learning (ML) approach to optimize PC conditions for fabricating methylammonium lead iodide (MAPbI3) films by quantitatively comparing their ultraviolet-visible (UV-vis) absorbance spectra to thermal annealed (TA) films using four similarity metrics. We perform Bayesian optimization coupled with Gaussian process regression (BO-GP) to minimize the similarity metrics. Refining PC conditions using active learning based on BO-GP models, we achieve a PC MAPbI3 film with an absorbance spectrum closely matching a TA reference film, which is further verified by its crystalline and morphological properties. Thus, we demonstrate that the UV-vis absorption spectrum can accurately proxy film quality. Additionally, we use an AI-based segmentation model for a more efficient grain size analysis. However, when we use the optimized PC condition to fabricate PSCs, we find that interaction between MAPbI3 and the hole transport layer (HTL) during PC critically degrades the PSC performance. By adding a buffer layer between the HTL and MAPbI3, the optimized PC PSCs produce a champion PCE of 11.8%, comparable to the TA reference of 11.7%. Using UV-vis similarity metrics instead of device PCE as the objective in our BO-GP method accelerates the optimization of PC processing conditions for MAPbI3 films. 

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2. Perovskite Solar Cells Enabled by the Synergy of Chlorine Additive and Scalable Rapid Photonic Annealing of Multiple Stacking Layers

   https://doi.org/10.1002/pip.70039  

   Vaezsis, Saeid; Ameri, Mohsen; Tang, Pei; Fedin, Igor; Li, Dawen (April 2026, Progress in Photovoltaics: Research and Applications)

   ABSTRACT Perovskite solar cells (PSCs) have gained significant attention due to their impressive power conversion efficiencies. However, developing rapid fabrication techniques for commercially feasible production of PSCs with high stability and efficiency requires more investigation. Also, as a feasible approach, additive strategy plays a crucial role in enhancing crystallinity and reducing defects of perovskite films, thereby improving the device performance. Herein, we explored the synergy of rapid UV‐LED annealing of multiple stacked layers while incorporating chlorine‐containing additive to enhance the morphology, crystallinity, and optoelectronic properties of perovskite absorber and demonstrated significant improvement of overall PSC performance, including both efficiency and stability. Specifically, chlorine incorporation leads to larger grain sizes, reduced defects and recombinations, and more efficient perovskite conversion with rapid UV‐LED annealing. The best all‐rapid photonic annealed (all‐RPA) PSC device with addition of chlorine‐containing additive demonstrates a PCE of 21.7% and retains over 80% of the initial PCE after 1000 h, which is the highest PCE ever reported on traditional MAPbI₃‐based PSCs fabricated with all kinds of optical annealing schemes. This work sheds light on the role of synergistic effects of UVA‐LED annealing and chlorine incorporation and paves the way for large‐scale manufacturing of perovskite‐based photovoltaics by using rapid and energy‐efficient UV‐LED photonic annealing. 

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3. Zinc Porphyrin-Functionalized Fullerenes for the Sensitization of Titania as a Visible-Light Active Photocatalyst: River Waters and Wastewaters Remediation

   https://doi.org/10.3390/molecules24061118  

   Regulska, Elzbieta; Rivera-Nazario, Danisha; Karpinska, Joanna; Plonska-Brzezinska, Marta; Echegoyen, Luis (March 2019, Molecules)

   Zinc porphyrin-functionalized fullerene [C60] derivatives have been synthesized and used to prepare titania-based composites. The electrochemical properties and HOMO and LUMO levels of the photosensitizers were determined by electrochemical measurements. Raman and IR techniques were used to study chemical groups present on the titania surface. Absorption properties of the composites were measured in the solid state by diffuse reflectance UV-Vis spectra (DRS). The zeta potential and aggregate sizes were determined using dynamic light scattering (DLS) and electrophoretic light scattering (ELS) techniques. Surface areas were estimated based on Brunauer–Emmett–Teller (BET) isotherms. The photocatalytic activity of the photocatalysts was tested using two model pollutants, phenol and methylene blue. The composite with the highest photocatalytic potential (1/TiO2) was used for river and wastewater remediation. The photodegradation intermediates were identified by LC-UV/Vis-MS/MS techniques. 

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4. New D‐A‐A’‐Configured Small Molecule Donors Employing Conjugation to Red‐shift the Absorption for Photovoltaics

   https://doi.org/10.1002/asia.202000635  

   Wang, Chun‐Kai; Che, Xiaozhou; Lo, Yuan‐Chih; Li, Ya‐Ze; Wang, Yung‐Hao; Forrest, Stephen R.; Liu, Shun‐Wei; Wong, Ken‐Tsung (June 2020, Chemistry – An Asian Journal)

   Four new donor-acceptor-acceptor' (D-A-A')-configured donors, CPNT, DCPNT, CPNBT, and DCPNBT equipped with naphtho[1,2-c:5,6-c']bis([1,2,5]-thiadiazole) (NT) or naphtho[2,3-c][1,2,5]thiadiazole (NBT) as the central acceptor (A) unit bridging triarylamine donor (D) and cyano or dicyanovinylene acceptor (A'), were synthesized and characterized. All molecules exhibit bathochromic absorption shifts as compared to those of the benzothiadiazole (BT)-based analogues owing to improved electron-withdrawing and quinoidal character of NT and NBT cores that lead to stronger intramolecular charge transfer. Favorable energy level alignments with C70 , together with the good thermal stability and the antiparallel dimeric packing render CPNT and DCPNT suitable donors for vacuum-processed organic photovoltaics (OPV)s. OPVs based on DCPNT : C70 active layers displayed the best power conversion efficiency (PCE)=8.3%, along with an open circuit voltage of 0.92 V, a short circuit current of 14.5 mA cm-2 and a fill factor of 62% under 1 sun intensity, simulated AM1.5G illumination. Importantly, continuous light-soaking with AM 1.5G illumination has verified the durability of the devices based on CPNT:C70 and DCPNT : C70 as the active blends. The devices were examined for their feasibility of indoor light harvesting under 500 lux illumination by a TLD-840 fluorescent lamp, giving PCE=12.8% and 12.6%, respectively. These results indicate that the NT-based D-A-A'-type donors CPNT and DCPNT are potential candidates for high-stability vacuum-processed OPVs suitable for indoor energy harvesting. 

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5. Fullertubes: A 30-Year Story of Prediction, Experimental Validation, and Applications for a Long-Missing Family of Soluble Carbon Molecules

   https://doi.org/10.1021/acs.accounts.4c00302  

   Stevenson, Steven; Dorn, Harry C (July 2024, Accounts of Chemical Research)

   During the last 30 years, theoretical scientists imagined segmental families of monolayer carbon tubules with fullerene-based end-caps. These fullertube molecules would possess structural features of both fullerenes (hemispherical end-caps) and tubular belts of single-walled carbon nanotubes (SWCNTs). Yet, their experimental verification remained elusive for decades. It was not until 2020–2023 that segmental families of fullertubes were finally confirmed in the lab. The shocking irony is that these fullertubes were unwittingly coproduced alongside fullerenes (e.g., C60, C70, C84) in both flame and electric arc soot since the 1990s. Yet, nobody knew these “hidden” families of fullertubes were experimentally present in their extracted soot due to their low abundance and the absence of isolation methodology. This eruption of fullertube discoveries in 2020–2023 was brought to fruition by structural data, both DFT and experimental. This “Treasure Trove” of new molecules during this four-year window occurred with only microgram quantities. Typically, milligram levels of purified samples are required for X-ray crystallography and 13C NMR structural analysis. The breakthrough for experimentally verifying the missing fullertubes was an aminopropanol reagent to selectively react with and remove spheroidal carbon (e.g., C60, C70, C84) as hydrophilic derivatives. In contrast, there was suppressed reaction with fullertubes, which remained in organic solvent. It is well established that high symmetry (3-, 5-, and 6-fold) hemispheres for C60-Ih and other fullerenes and metallofullerenes are prerequisite end-caps for fullertubes. For the case of [5,5] C130 fullertubes, this requirement results in only eight 3-, 5-, and 6-fold symmetry structural isomers possible from a total of 39,393 possible isolated pentagon rule (IPR) isomers. From this C130 list of 8 candidate isolated pentagon rule (IPR) high symmetry isomers, surprisingly only one structure matched the DFT polarizability versus chromatographic retention parameter (a new gold standard for isomer identification). The simultaneous emergence of DFT computations of other properties (e.g., total energy, HOMO–LUMO gap, UV–vis) for large carbon molecules provided support for structural determination. Experimental approaches (e.g., mass spectrometry, UV–vis, XPS, Raman, and STEM) provided additional layers of structural elucidation at the microgram level. For the first time, we developed a chemical isolation protocol that would allow the preparation and isolation of soluble pristine fullertubes in the range of C90–C200. To date, applications of SWCNTs for use in nanoscale computer applications requires purities greater than 99.999%. Although this stringent mandate has not yet been demonstrated using SWCNT samples, this high level of purity appears achievable for metallic [5,5] D5d-C120 and semiconductor [10,0] D5h-C120 [10,766] fullertubes. Moreover, commercial production of pristine fullertubes should easily be feasible by the flame method due to its continuous operation and inexpensive feedstock. For application development, theoretical and electrochemical experimental data show that fullertubes exhibit high catalytic activity in oxygen reduction reactions. In the medical sector, pristine fullertube dispersions exhibit antimicrobial effects on Mycobacterium smegmatis and M. abscessus. 

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