Anastasia Barabash

High efficiency inverted perovskite solar cells often rely on nickel‐containing hole‐selective interfaces such as NiOx. However, the use of nickel presents sustainability challenges, as the material is inherently toxic and cross‐contamination during end‐of‐life processing can compromise material recovery and recyclability. Here, we develop a nickel‐free hole‐selective interface material based on phenyl‐substituted phosphonic‐acid carbazole self‐assembled monolayers (Ph‐nPACz). Candidate molecules were identified through rational structure‐property screening of the substituents of the carbazole core, anchoring groups and linkers. Among this molecular family, Ph‐5PACz delivers the best overall performance, offering improved interfacial wettability and enhanced buried‐interface stability compared to the NiOx/Me‐4PACz reference. Devices incorporating Ph‐5PACz achieve a power conversion efficiency of 25.3%, compared to 21.7% for the control, driven by a higher fill factor and efficient charge extraction. The chemical robustness of the nickel‐free interface enables a closed‐loop recycling route unavailable to nickel‐based devices, with recycled‐ITO devices retaining close to 98% of their initial performance. Coupled life‐cycle and techno‐economic analyses further indicate substantial sustainability gains, including reduced energy demand, markedly lower raw metal usage and toxicity‐related impacts, and a generalized reduction of up to 29% across ReCiPe endpoint indicators.

We introduce ligand‐assisted epitaxial growth (LAEG) for lead‐halide perovskites, enabling the formation of high‐quality, single‐crystalline epitaxial microstructures. In this approach, ligands fulfill multiple critical functions: they regulate crystal growth by slowing crystallization kinetics, allowing the formation of epitaxial microcrystals with smooth surfaces and well‐defined morphologies; they protect the perovskite from environmental degradation; and they passivate surface states. Near‐ambient‐pressure X‐ray photoelectron spectroscopy confirms well‐preserved surface stoichiometry of CsPbBr ₃ enabled by ligand protection. The LAEG method is broadly applicable to different ligands, perovskite compositions, and substrates, consistently yielding higher material quality than non‐ligand‐assisted solution epitaxy. CsPbBr ₃ epitaxial microcrystals exhibit a high photoluminescence quantum yield of ∼50% and nearly temperature‐independent photoluminescence decay dynamics up to 80°C, demonstrating strong thermal robustness relevant for optoelectronic devices. Lasing is observed up to 90°C, and improved thermal management enhances operational lifetime. Micro‐resonator lasers grown on mica substrates exhibit record‐low threshold excitation powers among microcrystal‐based perovskite lasers, outperforming previously reported CsPbBr ₃ devices and those grown on PbS substrates due to favorable refractive‐index contrast enabling total internal reflection. Overall, LAEG provides a simple yet powerful route to high‐quality perovskite epitaxy and is expected to be extendable to lower‐dimensional perovskite systems with enhanced and tunable optical properties.

Organic small molecules possess significant potential for semitransparent optoelectronic applications due to their tunable optical properties and inherent transparency. However, tailoring these materials is challenging as their optoelectronic properties are sensitive to subtle structural changes, compounded by the existence of over a million potential structural designs. To address these complexities, we present a material discovery workflow that combines literature‐based molecule preselection with TDDFT calculations, creating customized small molecule structures with adjustable transparency windows. We identified fifty‐four small molecules with a D‐π‐A‐π‐D architecture, incorporating nine central (A) and six end (D) units connected by a thiophene π‐bridge. Through TDDFT calculations, we determined the theoretical absorption spectra and energy levels of the identified molecules. Ultimately, we synthesized twenty‐four molecules that exhibit promising transparency properties by selectively absorbing photons in the ultraviolet (UV) and near‐infrared (NIR) regions, with a significant optical transmission band relevant to the visible spectrum, which we will refer to as “optical window”. Characterization of the resultant small molecules revealed that six of them, in particular, exhibited selective absorption with the broadest “optical window”. We believe that our study will provide valuable insights to establish an effective material discovery workflow for highly transparent conjugated organic small molecules.

Guided by phase-field simulations, a pre-coated 2D perovskite layer enables the growth of void-free perovskite layers over one-micron-thick, achieving high-efficiency, fully printed solar cells.

Perovskite solar cells (PSCs) have recently achieved over 26 % power conversion efficiency, challenging the dominance of silicon‐based alternatives. This progress is significantly driven by innovations in hole transport materials (HTMs), which notably influence the efficiency and stability of PSCs. However, conventional organic HTMs like Spiro‐OMeTAD and PTAA, although highly efficient, suffer from thermal degradation, moisture ingress, and high cost. This study explores the potential of iminodibenzyl, a moiety known for its strong electron‐donating capabilities in pharmaceutical applications, as a novel HTM. A series of fluorene‐based derivatives incorporating iminodibenzyl (TMF‐2 and TDF‐2) and diphenylamine (TMF‐1 and TDF‐1) units were synthesized and characterized. The new HTMs demonstrated commendable optical, electrochemical, and thermal properties, as well as enhanced photostability. Among them, TDF‐2 achieved a power conversion efficiency (PCE) of 19.38 %, the highest of the new materials. Although these efficiencies are slightly lower than the benchmark PTAA (20.20 %), the study underscores the potential of iminodibenzyl to enhance photostability and increase HOMO levels, making it a promising candidate for future HTM development in PSCs.

Aerosol jet printing (AJP) is an effective method for manufacturing organic photovoltaic (OPV) devices for indoor use. Its noncontact deposition, without posttreatment, and high‐resolution 3D pattern printing capabilities make it ideal for using functional nanomaterial inks. This study explores ultrasonic AJP (uAJP) atomization to deposit silver nanowires (AgNW) as the top electrode layer (TEL) in OPV devices. The OPV stack is fabricated up to the hole transport layer using high‐throughput screening (HTS) methodologies. Different deposition techniques, including spin‐coating, blade‐coating, and uAJP of AgNW inks, as well as thermal evaporation of silver, are compared. Scanning electron microscopy analysis shows that the E2X AgNW ink formed a compact TEL layer. Combining HTS setups, right selection of interlayers and uAJP method, automated, solution‐processed OPV devices with power conversion efficiencies of 9.54% on an active layer of 0.0232 cm² are achieved, the highest reported for OPV devices using uAJP AgNW inks as top electrodes.

Perovskite solar cells (PSCs) have become a research hotspot since their dramatic increase in power conversion efficiency (PCE), surpassing 26% due to advances in cell engineering and interfacial layers. Within the last factor, hole transporting materials play a crucial role in enhancing device performance and stability. Among several molecular building blocks, BODIPYs are attractive for the design of novel hole transporting material (HTMs) due to their outstanding photophysical and charge transport properties easily tuned by synthetic modifications. Herein, the synthesis of five new BODIPY‐based HTMs PyBDP 1–5 are reported, functionalized at the meso‐ and α‐ positions with pyrenyl and arylamino units, respectively. The resulting compounds exhibit broad absorption in the visible region, remarkable thermal stability, narrow bandgaps, suitable energy levels, and good hole extraction capability, as subtracted from experimental and computational characterizations. The performance of the BODIPY derivatives as HTMs is evaluated in planar inverted (p‐ i ‐n) PSCs and compared to commonly used PTAA, resulting in highly efficient systems, reaching PCEs very close to that obtained with the reference polymer (21.51%). The incorporation of these BODIPY‐based HTMs result in an outstanding PCE of 20.37% for devices including PyBDP‐1 and 19.97% for devises containing PyBDP‐3 , thus demonstrating that BODIPY derivatives are a promising alternative to obtain simple and efficient organic HTMs.

Metal halide perovskite semiconductors have demonstrated remarkable progress not only in photovoltaics and X‐ray detection but also in laser technologies. Particularly appealing is the simplicity with which micro‐crystallites can be epitaxially grown, thereby forming micro‐resonators suitable for lasing. Here, the laser threshold is optimized by selecting excitation laser parameters and by improving material quality. The latter process is conducted for formamidinium lead tribromide, emitting in the green spectral range. Depending on the growth method and parameters, the sizes of the micro‐resonators can be tuned between ≈3 and 23 micrometers. Under laser excitation systematically lower thresholds are observed for micro‐resonators in the 4–7 micrometer size range, than for larger ones, irrespective of growth method. Among three optimized growth methods, epitaxial growth via antisolvent vapor‐assisted crystallization exhibits the smallest threshold powers, indicating the highest material quality. This conclusion is supported by hyperspectral microscopic luminescence imaging and by transient photoluminescence. The best laser structures exhibit record threshold powers for epitaxially grown perovskites, indicating that the selected antisolvent vapor epitaxial growth holds great promises also for other perovskite materials.

Epitaxial growth methods usually need dedicated equipment, high energy consumption to maintain pure vacuum conditions and evaporation of source materials, and elevated substrate temperatures. Solution epitaxial growth requires nothing of that but is rarely used because the achieved microstructures are of low quality, not homogeneous, and finally exhibit worse performances in devices. Here, an antisolvent‐vapor‐assisted‐crystallization of metal‐halide‐perovskites as a method overcoming these disadvantages is demonstrated. The methylammonium lead tribromide exhibits van‐der‐Waals type of epitaxial growth on mica substrates, resulting in micro‐crystallites whose shape can be controlled to be either triangular micro‐prism or micro‐cuboid. These micro‐crystallites act as optical resonators supporting various optical modes and lasing is achieved under optical excitation with low thresholds and record high environmental stability. Selecting suitable resonators from a large variety of sizes allows control of mode spacing and finally mono‐mode operation, considered to be an important feature of semiconductor laser devices. The achieved results are essentially competitive to those obtained by vapor phase epitaxial microstructures, highlighting that epitaxy of high‐quality optoelectronic device structures is feasible by minimum technological efforts and energy consumption, which are of increasing importance considering issues such as global warming and the current energy crisis.