Photovoltaic devices based on organic–inorganic hybrid perovskites have engaged tremendous attention due to the enormous increase in power conversion efficiency (PCE). However, defect states formed at grain boundaries and interfaces hinder the achievement of PCE. A prospective strategy to both reduce interfacial defects and control perovskite growth is the passivation of interfaces. The passivation of the electron-transporting layer/perovskite interface with ultrasmall carbon dots (CDs) with suitable chemical composition and functional groups on their surface may simultaneously affect the morphology of a perovskite layer, facilitate charge carriers extraction, and suppress interfacial recombination. Here, we show that CDs synthesized from diamine precursors may be used as an interlayer at the SnO₂/FACsPbI₃ interface. Ultrasmall CDs form a smooth, thin layer, providing better perovskite layer morphology. CD interlayers result in an increased average perovskite grain size, suppress the formation of small grains, and improve charge carriers’ extraction. As a result, photovoltaic devices with CD interlayers demonstrate a higher PCE due to the increased short-circuit current density and fill factor. These findings provide further insight into the construction of interfaces based on carbon nanomaterials.

Solution-processed perovskite solar cells (PSCs) have demonstrated a tremendous growth in power conversion efficiency (PCE). A high-quality, defect-free perovskite-based active layer is a key point to enhance PSC performance. Introduction of additives and interlayers have proved to be an effective tool to passivate surface defects, control crystal growth, and improve PSC stability. Antisolvent engineering has emerged recently as a new approach, which aims to adjust perovskite layer properties and enhance the PCE and stability of PSC devices. Here, we demonstrate that carbon dots (CDs) may serve as a prospective additive for antisolvent engineering. Nitrogen-rich amphiphilic CDs were synthesized from amines by a solvothermal method and used as an additive to chlorobenzene for a perovskite layer fabrication. The interaction between perovskite and functional groups in CDs promotes improved crystallization of an active perovskite layer and defects passivation, bringing higher PSCs efficiency, stability, and suppressed hysteresis. Under optimized CD concentration, the maximum PCE increased by 34% due to the improved short-circuit current and fill factor, and the device maintains 87% of its initial efficiency after 6 d of storage under ambient conditions.

The growing deployment of remotely operating low-power underwater monitoringdevices dictate the need for a persistent energy source enabling stable performanceor complementing the main power supply. Perovskite solar cells (PSCs) possess highpotential for underwater energy supply owing to their semiconductor properties andlow-cost fabrication process compared to classic silicon solar cells. However, to overcome the direct chemical reaction of perovskites with water, reliable encapsulation andnew contact output design are critically needed. To this end, we for the first timeimplemented maskless metallization by modified laser-induced chemical liquid deposition (LCLD) to produce copper-patterned substrates deposited from deep eutecticsolvent (DES) for safe encapsulation of humidity-sensitive PSCs for underwater operation with power conversion efficiency (PCE) exceeding 20%. The resulting copperelectric contacts prevent water and air leakage into the device during the underwatermeasurements because of their thickness of about 1.2 µm and roughness around 200nm, enabling retention of PCE at a 95%-level relative to the bare device measured atstandard conditions. This approach paves the way for encapsulation of next-generationsolar cells operating at high humidity and underwater environments.

On-going development of carbon dots (CDs) for different applications calls for search of novel methods for their synthesis and surface functionalization. For fabrication of light-emitting devices (LEDs), CDs should be soluble in non-polar solvents that are used for ink-printing of their functional layers, apart from the obvious requirement of bright luminescence. Herein, we introduce amphiphilic CDs synthesized from a mixture of benzoic acid and ethylenediamine in acetylacetone, which satisfy both above mentioned requirements. These CDs are quasi-spherical nanoparticles 20-50 nm in size, holding aliphatic, carbonyl, amide, imine, and carbamate groups at the surface which renders them amphiphilic and soluble in a variety of substances with relative polarity ranging from 0.002 to 1, such as toluene, chloroform, alcohols, and water. By variation of the molar ratio of benzoic acid and ethylenediamine, an optimal value for photoluminescence quantum yield of 36 % in non-polar solvents is achieved. Importantly, these CDs are easily mixable with a charge transport polymer – polyvinylcarbazole, a common component of organic LEDs. As a demonstration of use of developed amphiphilic CDs in LEDs, green emitting charge-injection devices are fabricated with a broad emission band centered at 515 nm, maximal luminance of 1716 cd/m2, and ССT of 5627 K.

Исследование оптических свойств аминированных углеродных точек на основе лимонной кислоты и этилендиамина

Polyelectrolytes represent a low‐cost and effective platform for tailoring charge extraction interfaces in inverted perovskite solar cells (PSCs). In this work, we introduce a protonated polyethyleneimine (PEI) layer (pH = 2) between the ITO electrode and the PTAA hole transport layer to increase the apparent work function of ITO by 0.066 eV and reduce contact resistance and the work‐function mismatch with PTAA from 0.170 to 0.104 eV. By incorporating low concentrations of PEI (0.3–1 mg/mL), we significantly increased the open‐circuit voltage up to 1.143 V and achieved a peak power conversion efficiency of 23.45%. The PEI‐modified devices maintain superior photovoltaic performance not only under standard AM 1.5 G illumination, but also at low sunlight intensities (30 and 50 mW/cm ² ) and under indoor illumination conditions. These results highlight the potential of protonated polyelectrolyte interlayers for developing efficient and versatile PSCs suitable for both outdoor and ambient‐light applications.