ABSTRACT Metal halide perovskite field‐effect transistors (PeFETs) have rapidly gained recognition as leading candidates for next‐generation electronic and optoelectronic technologies, owing to their exceptional optoelectronic properties, facile solution processability, and notable mechanical flexibility. Nevertheless, the practical deployment of high‐performance PeFETs is significantly impeded by persistent challenges, including ion migration, hysteresis effects, and environmental instability, which collectively hinder their widespread adoption. This review offers a thorough and up‐to‐date overview of recent progress in the field of PeFETs, with particular emphasis on advances in material engineering, device architecture optimization, and innovative processing techniques designed to enhance device performance. The discussion encompasses the fundamental physics governing charge transport in perovskite semiconductors, with a focus on the influence of defect chemistry, interface engineering, and stability considerations. Special attention is devoted to a comparative analysis of tin‐based and lead‐based PeFETs, elucidating their respective charge transport mechanisms, benefits, and limitations. The review concludes by identifying the principal challenges and outlining future research directions that are essential for realizing the full potential of perovskite transistors in delivering high‐speed, flexible, and cost‐effective electronic devices.

Surpassing the Shockley‐Queisser (S‐Q) limit to realize photovoltaic efficiencies that significantly exceed those of traditional silicon solar cells (SSCs) remains a fundamental aspiration within the solar energy research community. The advent of multi‐junction tandem cells presents a highly promising strategy to achieve this ambitious goal. Owing to their adjustable bandgaps and exceptional power conversion efficiencies (PCEs), perovskite solar cells (PSCs) have emerged as leading candidates for the top cell position in tandem device architectures, thereby advancing the frontier of next‐generation photovoltaic technologies. Recent advancements have propelled the certified PCE of two‐terminal monolithic perovskite/silicon tandem solar cells (PSTs) to 34.85% as of 2025, significantly surpassing the 27.81% efficiency of single‐junction crystalline silicon cells and the 27.3% achieved by standalone PSCs. This review synthesizes recent progress in the design and optimization of perovskite top cells, emphasizing strategies that enable highly efficient and stable monolithic PSTs. Particular attention is given to fabrication techniques that ensure robust integration of perovskite and charge transport layers onto the silicon substrate, whether the silicon surface is polished or textured. The review also examines state‐of‐the‐art approaches for modifying the bulk, surface, and interfaces of functional layers, as well as electrode engineering, all aimed at optimizing carrier transport and reducing recombination losses. Finally, the persistent challenges facing the field are discussed and perspectives and design guidelines are offered to propel future research directions, with the ultimate goal of advancing perovskite/silicon tandem technology toward widespread industrial adoption.

Although organic light-emitting diodes (OLEDs) are considered a mature technology, further enhancements in their efficiency are of paramount importance for advancing their incorporation in high-quality displays and flexible, wearable, electronic devices. In this regard, we propose an innovative approach, focusing on strategic modifications to the hole transport layer (HTL) through the integration of core-shell nanoparticles. Silver nanoparticles (Ag-NPs) encapsulated in a tungsten polyoxometalate compound (POM) are embedded within the prototype poly(3,4-ethylenedioxythiophene)-poly(styrenesulphonate) (PEDOT:PSS) to form the modified HTL. Our work reveals the pivotal plasmonic role of Ag-NPs in enhancing OLED device performance based on commercially available conjugated polymers. Comprehensive analyses, including UV-Vis absorption spectroscopy, atomic force microscopy, photoluminescence spectroscopy, and electrical measurements, confirm the influence of the POM encapsulated Ag-NPs on improving the device efficiency. This is attributed to the synergistic influence of enhanced hole injection and conductivity and beneficial optical effects (i.e. the Localized Surface Plasmon Resonance (LSPR) and, likely, light scattering of the POM-Ag NPs in the core-shell configuration, depending on their diameter), contributing to enhanced carrier balance and exciton recombination rate. Comparison with POM gold NPs (POM-Au NPs) highlights the distinct advantages of POM-Ag NPs. Our work reveals the potential of this innovative approach to contribute to the evolution of high-performance OLEDs, ensuring a visually compelling and efficient future.

Charge injection and transport interlayers play a crucial role in many classes of optoelectronics, including organic and perovskite ones. Here, we demonstrate the beneficial role of carbon nanodots, both pristine and nitrogen-functionalized, as electron transport materials in organic light emitting diodes (OLEDs) and organic solar cells (OSCs). Pristine (referred to as C-dots) and nitrogen-functionalized (referred to as NC-dots) carbon dots are systematically studied regarding their properties by using cyclic voltammetry, Fourier-transform infrared (FTIR) and UV–Vis absorption spectroscopy in order to reveal their energetic alignment and possible interaction with the organic semiconductor’s emissive layer. Atomic force microscopy unravels the ultra-thin nature of the interlayers. They are next applied as interlayers between an Al metal cathode and a conventional green-yellow copolymer—in particular, (poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(1,4-benzo-{2,1′,3}-thiadiazole)], F8BT)—used as an emissive layer in fluorescent OLEDs. Electrical measurements indicate that both the C-dot- and NC-dot-based OLED devices present significant improvements in their current and luminescent characteristics, mainly due to a decrease in electron injection barrier. Both C-dots and NC-dots are also used as cathode interfacial layers in OSCs with an inverted architecture. An increase of nearly 10% in power conversion efficiency (PCE) for the devices using the C-dots and NC-dots compared to the reference one is achieved. The application of low-cost solution-processed materials in OLEDs and OSCs may contribute to their wide implementation in large-area applications.

Two gallium porphyrins, a tetraphenyl GaCl porphyrin, termed as (TPP)GaCl, and an octaethylporphyrin GaCl porphyrin, termed as (OEP)GaCl, were synthesized to use as an electron cascade in ternary organic bulk heterojunction films. A perfect matching of both gallium porphyrins’ energy levels with that of poly(3-hexylthiophene-2,5-diyl) (P3HT) or poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) polymer donor and the 6,6-phenyl C71 butyric acid methyl ester (PCBM) fullerene acceptor, forming an efficient cascade system that could facilitate electron transfer between donor and acceptor, was demonstrated. Therefore, ternary organic solar cells (OSCs) using the two porphyrins in various concentrations were fabricated where a performance enhancement was obtained. In particular, (TPP)GaCl-based ternary OSCs of low concentration (1:0.05 vv%) exhibited a ~17% increase in the power conversion efficiency (PCE) compared with the binary device due to improved exciton dissociation, electron transport and reduced recombination. On the other hand, ternary OSCs with a high concentration of (TPP)GaCl (1:0.1 vv%) and (OEP)GaCl (1:0.05 and 1:0.1 vv%) showed the poorest efficiencies due to very rough nanomorphology and suppressed crystallinity of ternary films when the GaCl porphyrin was introduced to the blend, as revealed from X-ray diffraction (XRD) and atomic force microscopy (AFM). The best performing devices also exhibited improved photostability when exposed to sunlight illumination for a period of 8 h than the binary OSCs, attributed to the suppressed photodegradation of the ternary (TPP)GaCl 1:0.05-based photoactive film.

Solar cells based on metal halide perovskite and polymer donor:nonfullerene acceptor blend absorbers have recently witnessed a significant rise in their photovoltaic performance. However, they still suffer from some instability issues originating from the inferior interface quality and poor nanomorphology of the absorber layer. In this work, a series of functionalized boron‐dipyrromethene, BODIPY, molecules are introduced as ultrathin interlayers at the absorber/electron transport layer interface. This study indicates that BODIPY compounds with a high molecular dipole moment can enhance the device performance mainly due to better interface energy level alignment. They also induce passivation of defect traps and improvement in the charge transport properties of the absorber layer coated on top of them. Among the various compounds used, amino‐functionalized BODIPY, owing to the synergetic effect of the abovementioned factors, enables the highest power conversion efficiency in organic (15.69%) as well as in perovskite solar cells (20.12%). Amino‐functionalized BODIPY also demonstrates an enhanced stability under continuous illumination (in nitrogen) without and with heating (at 65 °C) for 1000 h. These results pave the way for the implementation of molecules with tailor‐made functionalities in high efficiency and stable solution‐based photovoltaic devices of the future.

Earth-abundant transition metal oxides deposited at room temperature with low-cost methods suitable for large area manufacturing can offer advances in many fields of energy related devices. Here we report the room-temperature deposition of a fluorine-doped tantalum pentoxide using a home-made, low-cost hot-wire deposition system. This novel tantalum oxyfluoride material is super hydrophobic, ultra-transparent within the visible spectrum, and possesses adequate conductivity and suitable valence band and conduction band extrema for acting as efficient hole extraction and electron blocking layer in organic solar cells with the forward architecture. By inserting this material in the form of nanoparticles deposited on top of the commonly used as hole transport layer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate, higher efficiencies compared to the reference cells without the nanoparticles were demonstrated in solar cells based on blends of polymer donors with either a fullerene (where maximum achieved efficiency was improved from 6.07% to 7.90%) or a non-fullerene acceptor (reaching values of 13.48% compared to 11.32% of the reference cell). Moreover, significant improvement in device stability was achievd in unencapsulated devices continuously exposed in a humid environment for 500 h. This work demonstrates the unambiguous potential of well-designed metal oxide materials as charge transport and blocking interlayers and protective buffers in organic solar cells and beyond.

High-performance perovskite light-emitting diodes (PeLEDs) require a high quality perovskite emitter and appropriate charge transport layers to facilitate charge injection and transport within the device. Solution-processed n-type metal oxides represent a judicious choice for the electron transport layer (ETL); however, they do not always present surface properties and energetics compatible with the perovskite emitter. Moreover, the emitter itself exhibits poor nanomorphology and defect traps that compromise the device performance. Here, we modulate the surface properties and interface energetics between the tin oxide (SnO 2 ) ETL with the perovskite emitter by using an amino functionalized difluoro{2-[1-(3,5-dimethyl-2 H -pyrrol-2-ylidene- N )ethyl]-3,5-dimethyl-1 H -pyrrolato- N }boron compound and passivate the defects present in the perovskite matrix with carbon-polymer core–shell quantum dots inserted into the perovskite precursor. Both these approaches synergistically improve the perovskite layer nanomorphology and enhance the radiative recombination. These properties resulted in the fabrication of near-infrared PeLEDs based on formamidinium lead iodide (FAPbI 3 ) with a high radiance of 92 W sr −1 m −2 , an external quantum efficiency (EQE) of 14%, reduced efficiency roll-off and prolonged lifetime. In particular, the modified device retained 80% of the initial EQE (T 80 ) for 33 h compared to 6 h of the reference cell.

We replicated photonic nanostructures from the adaxial epidermis of flower petals onto a light polymerized coatings using low-cost nanoimprint lithography at ambient temperature. We demonstrate a clear link between the nanomorphology and function of the engineered nanocoatings and found that those consisting of individual nanoprotrusions feature better antireflection while those with conical structures, merged or individual, present superhydrophobic function. Especially, hierarchical conical photonic nanostructures with sub-wavelength features depict excellent omnidirectional antireflection property and ultrahydrophobicity superior to that of the natural Lotus leaf. These multifunctional nanocoatings are applied to confer enhanced light trapping, water repellence, ultra-violet light and environmental moisture protection features in perovskite solar cells that attained a power conversion efficiency of 24.61% (21.01% for the reference cell) without any additional device optimization. Added to the merits, the nanocoatings also enabled stable operation under real world conditions. Our engineering approach provides a simple way to produce multifunctional nanocoatings optimized by nature’s wisdom.

Here, we report photonic nanostructures replicated from the adaxial epidermis of flower petals onto light-polymerized coatings using low-cost nanoimprint lithography at ambient temperature. These multifunctional nanocoatings are applied to confer enhanced light trapping, water repellence, and UV light and environmental moisture protection features in perovskite solar cells. The former feature helps attain a maximum power conversion efficiency of 24.61% (21.01% for the reference cell) without any additional device optimization. Added to these merits, the nanocoatings also enable stable operation under AM 1.5G and UV light continuous illumination or in real-world conditions. Our engineering approach provides a simple way to produce multifunctional nanocoatings optimized by nature’s wisdom.

The presence of defects formed during the growth and crystallization of perovskite films is a limiting factor to achieve high efficiency and stability in perovskite solar cells.

An overview on recent advances in the fundamental understanding of how interfaces of mesoscopic perovskite solar cells (mp-PSCs) with different architectures, upon incorporating various charge transport layers, influence their performance.

Further advancements in organic light emitting diodes (OLEDs) using commercially available, low-cost materials is of high significance. Here, we report the application of commercially available chromophores as room temperature processed electron injection layers (EILs) in the conventional OLED architecture. The facile solution-processing of these chromophores, namely, 4‐dimethylamino‐4′‐nitrostilbene (DANS) and 1‐(4‐(dimethylamino)phenyl)‐6‐phenyl‐1,3,5‐hexatriene, along with the presence of nitrogen atom in their structure, which is expected to induce the formation of a negative interfacial dipole at the cathode interface, have motivated their use as EILs. Improved performance of the OLEDs using these chromophores was obtained. Especially, the OLED using DANS exhibited the highest luminous efficiency, power efficiency and external quantum efficiency values of 8.7 cd A −1 , 6.75 lm W −1 and 2.9%, respectively, which represented a significant improvement compared to the reference device without the EIL (1.2 cd A −1 , 0.7 lm W −1 and 0.4%, respectively). A variety of experimental and simulated results demonstrated that this enhancement is attributed to increased electron injection leading to balanced electron and hole currents, especially in the DANS embedding device. Additionally, we calculated significant broadening of the emission zone profile across the entire organic emitter in the devices using the chromophores, thus increasing the probability of radiative recombination and photon emission.

The surface, interfaces and grain boundaries of a halide perovskite film carry critical tasks in achieving as well as maintaining high solar cell performance due to the inherently defective nature across their regime. Passivating materials and felicitous process engineering approaches have significant ramifications in the resultant perovskite film, and the solar cell's overall macroscale properties as they dictate structural and optoelectronic properties. Herein, we exploit a vast number of defect engineering approaches aiming to increase the performance and the stability of perovskite solar cells, especially against humidity, continuous illumination, and heat. This review begins with the perovskite materials' fundamental structural properties followed by the advances made to induce higher stabilization in perovskite solar cells by fine-tuning materials chemistry design parameters. We continue by summarizing defect passivation strategies based on molecular entities' application, including suitable functional groups that enable sufficient surface, bulk and grain boundary passivation, morphology, and crystallinity control. We also present methods to control the density of defects through the variation of processing conditions, solvent annealing and solvent engineering approaches, gas-assisted deposition methods, and use of self-assembled monolayers, as well as colloidal engineering and coordination surface chemistry. Finally, we give our perspective on how a combined understanding of materials chemistry aspects and passivation mechanisms will further develop high-efficiency and stability perovskite solar cells.

In this work, we propose a simple and effective approach to modify the optoelectronic properties of the commonly used poly(3,4-ethylenedioxylthiophene):poly(styrene sulfonate) (PEDOT:PSS) and consequently to improve hole injection and transport in organic light emitting diodes (OLEDs) using emissive layers based on a fluorescence copolymer. In particular, two triphenylsulfonium (TPS) salts that consist of the same TPS cation and two different counter anions, in particular, hexafluoroantimonate (SbF6) and trifluoromethane sulfonate (Triflate) were added in the PEDOT:PSS solution in various concentrations and the composite films were fully characterized for surface and optoelectronic properties and subsequently we employed as hole injection layers (HILs) in OLEDs. It is demonstrated that both, the counter anion and the concentration of TPS-salts in the PEDOT: PSS matrix play significant role in the optoelectronic properties of the composite and thus in the device performance. Although all TPS-salt modified PEDOT:PSS films exhibited higher work function (WF) values relative to the undoped one thus resulting in more efficient hole injection than pristine PEDOT:PSS, the PEDOT:PSS:TPSTriflate with the lower concentration (10:1 v/v) showed the highest luminous (LE) and power efficiency (PE) values of 27.04 cd A-1 and 6.26 lm W-1, respectively. This extraordinary performance was ascribed to a significant increase in the conductivity of the composite film combined with the formation of an interface exciplex between the TPS-Triflate (acceptor) and the emissive copolymer (donor). This interfacial electroplex strongly confines the generated excitons and prevents their diffusion towards aluminum cathode which acts as exciton quencher.

As organic solar cells (OSCs) and perovskite solar cells (PVSCs) move closer to commercialization, further efforts toward optimizing both cell efficiency and stability are needed. As interfaces strongly affect device performance and degradation processes, interfacial engineering by employing various materials as hole transport layers (HTLs) and electron transport layers (ETLs) has been a very active field of research in OSCs and PVSCs. Among them, inorganic materials exhibit significant advantages in promoting device performance due to their excellent charge transporting properties and intrinsic thermal and chemical robustness. In this review, an extensive overview is provided of inorganic semiconductors such as copper-based ones with emphasis on copper iodide and copper thiocyanate, transition metal chalcogenides, nitrides and carbides as well as hybrid materials based on these inorganic compounds that have been recently employed as HTLs and ETLs in OSCs and PVSCs. Following a short discussion of the main optoelectronic and physical properties that interfacial materials used as HTLs and ETLs should possess, the functionalities of the aforementioned materials as interfacial, charge transport, layers in OSCs and PVSCs are discussed in depth. It is concluded by providing guidelines for further developments that could significantly extend the implementation of these materials in solar cells.

Organic and perovskite solar cells have recently emerged as promising candidates for next-generation solar energy technologies due to their low-cost solution-based fabrication over large areas even on flexible substrates, while offering the possibility of on-chip integration and patterning for custom-designed applications. A key concern over these emerging technologies is their poor operational stability. In a typical device architecture, the organic or perovskite absorber is usually inserted between an electron and a hole transport (extraction) layer in order to match the energetic differences present at the heterointerfaces with the respective contacts. As these layers considerably influence the device performance and operational stability, they have witnessed intense research efforts in recent years resulting in the development of novel materials. Conductive or insulating polymers, non-polymer molecular materials and transition metal oxides are among the most studied classes of interfacial materials. In this review article, we focus on the application of molecular materials, but excluding polymers, either organic or inorganic, to engineer the interfaces in these devices due to their ease of synthesis and facile functionalization of their structure to meet the requirements for successful device modification. We also include ionic compounds of well-defined stoichiometry such as CuSCN, ionic liquids and compounds of molecular anions as the polyoxometalates. We provide a comprehensive account of various molecular interlayers for organic and perovskite solar cell devices. We highlight the origin of enhanced performance and device lifetime and provide a detailed outlook for a focused future development of these materials.

The design and development of novel materials with superior charge transport capabilities plays an essential role for advancing the performance of electronic devices. Ternary and doped oxides can be potentially explored because of their tailored electronic energy levels, exceptional physical properties, high electrical conductivity, excellent robustness and enhanced chemical stability. Here, a route for improving metal oxide characteristics is proposed by preparing a novel ternary oxide, namely, carbon-doped tantalum dioxyfluoride (TaO2FCx) through a straightforward synthetic route and exploring its effectiveness as an electron transport material in optoelectronic devices based on organic semiconductors. Among other devices, we fabricated fluorescent green organic light emitting diodes with current efficiencies of 16.53 cd/A and single junction non-fullerene organic solar cells reaching power conversion efficiencies of 14.14% when using the novel oxide as electron transport material. Our devices also exhibited the additional advantage of high operational and temporal stability. Non-fullerene OSCs based on the novel compound showed unprecedented stability when exposed to UV light in air due to the non-defective nature of TaO2FCx, We employed a tank of experiments combined with theoretical calculations to unravel the performance merits of this novel compound. This study reveals that properly engineered ternary oxides, in particular, TaO2FCx or analogous materials can enable efficient electron transport in organic optoelectronics and are proposed as an attractive route for the broader field of optoelectronic devices including metal-organic perovskite, colloidal quantum dot and silicon optoelectronics.

We report on the effect of lithium doping of zinc oxide used as electron-transport layer in organic solar cells based on both fullerene and non-fullerene acceptors. The experimental and theoretical results indicate that lithium ions intercalated within the ZnO lattice as dopants replace interstitial zinc defects that act as trap states and give rise to a higher electron conductivity without significantly altering work function and valence band edge. The enhanced electron carrier extraction/collection efficiency, the suppressed bimolecular and interface trap-assisted recombination losses and the higher electron mobility of the photoactive blend synergistically contribute to the superior performance of PTB7-Th:PC71BM-based fullerene devices utilizing doped ZnO layers with an optimized lithium concentration of 5 wt %. Such devices increased their maximum PCE from 8.59% (average 8.05%) to 10.05% (average 9.53%) while, simultaneously, boosting their long-term stability. Moreover, non-fullerene solar cells based on the PTB7-Th:IT-4F blend exhibited PCEs up to 8.96% and maintained more than 80% of their initial efficiency after 1000 h storage in the dark upon using the lithium modified ZnO electron transport layer.

Photovoltaic devices based on organic semiconductors and organo-metal halide perovskites have not yet reached the theoretically predicted power conversion efficiencies while they still exhibit poor environmental stability. Interfacial engineering using suitable materials has been recognized as an attractive approach to tackle the above issues. We introduce here a zinc porphyrin-triazine-bodipy donor-π bridge-acceptor dye as a universal electron transfer mediator in both organic and perovskite solar cells. Thanks to its "push-pull" character, this dye enhances electron transfer from the absorber layer toward the electron-selective contact, thus improving the device's photocurrent and efficiency. The direct result is more than 10% average power conversion efficiency enhancement in both fullerene-based (from 8.65 to 9.80%) and non-fullerene-based (from 7.71 to 8.73%) organic solar cells as well as in perovskite ones (from 14.56 to 15.67%), proving the universality of our approach. Concurrently, by forming a hydrophobic network on the surface of metal oxide substrates, it improves the nanomorphology of the photoactive overlayer and contributes to efficiency stabilization. The fabricated devices of both kinds preserved more than 85% of their efficiency upon exposure to ambient conditions for more than 600 h without any encapsulation.