Embedding a third and/or fourth component into a binary blend active layer of organic photovoltaics (OPVs) is a promising approach to achieve high‐performance photovoltaic cells and modules. This multicomponent strategy favors absorption broadening via additional components. Quaternary OPV (QOPV) blends have four components in three possible configurations: (i) a donor and three acceptors, (ii) two donors and two acceptors, or (iii) three donors and an acceptor. Although quaternary systems have only been relatively recently studied compared to other systems in OPVs, leveraging the synergistic effects of the four components leads to record power conversion efficiencies, currently approaching 20%. QOPVs provide ample material choices for compatibility and channels for charge transfer mechanisms, possibly leading to optimized morphology and orientation. Reviewing recent progress in advancing QOPVs is essential for understanding their contribution to the OPV field. The review mainly discusses research progress in QOPVs with a keen interest in their various configurations, semitransparency, and outdoor and indoor applications. It describes the not‐well‐understood QOPV's general working mechanism. This review explores high‐performance QOPVs based on the fourth component's contribution as a donor, acceptor, or dye molecule and beyond in photovoltaic applications. Finally, there is a discussion around QOPV's outlook and projected future research directions in this field. This review intends to provide an overview of the quaternary systems approach to OPVs and inform current and future researchers on investigating the full spectrum of OPVs.

This study presents the influence of pH control agents and pH value on the physical properties of ZnO thin films obtained by chemical bath deposition. ZnO thin films were synthesized on glass substrates using precursor solutions of different pHs prepared from two bases: sodium hydroxide (NaOH) and ammonia (NH₃). The effect of pH values on the morphological, structural, and optical properties of ZnO thin films was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and UV–Visible spectroscopy. XRD results showed that all the synthesized ZnO thin films are polycrystalline and crystallize in a hexagonal wurtzite structure. The crystallite size, calculated using the Debye–Scherrer formula, varied from 10.50 nm to 11.69 nm for ZnO thin films obtained with NH₃ and from 20.79 nm to 27.76 nm for those obtained with NaOH. FTIR analysis confirmed the presence of functional groups. SEM images indicated that not only the base but also the pH affects the morphology of the films, giving rise to different granular shapes. Overall, the ZnO thin films obtained with NaOH looked more mesoporous compared to those obtained with NH₃. Optical characterization results showed that whatever the base used, the pH of the precursor solution affected the ZnO thin film transmittance. Films synthesized with NH₃ exhibited the best transmittance (80%) at pH 8.5, while the best transmittance (81%) of films synthesized with NaOH was obtained at pH 8 in the visible region. Based on optical and morphological properties, ZnO films obtained from NH₃ at pH 8.5 are found to be more suitable as photoanodes in dye-sensitized solar cells.

This study investigates the effect of deposition time on the structural, morphological, and optical properties of ZnO thin films synthesized by single-step chemical bath deposition (CBD) without the use of a seed layer. The films were systematically characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and UV-Visible spectroscopy in order to establish correlations between growth conditions and film properties. XRD analysis confirmed that all synthesized films are polycrystalline and crystallize in the hexagonal wurtzite structure, with average lattice parameters of a = 3.247 Å and c = 5.209 Å. The crystallite size increased slightly from 13.27 nm to 14.05 nm with increasing deposition time, indicating improved structural ordering and crystallinity. FTIR spectra verified the presence of characteristic Zn–O vibrational modes together with surface hydroxyl groups and other functional bonds related to the growth process. SEM images revealed a strong dependence of surface morphology on deposition time: ZnO microrods evolved from loosely distributed to more compact and densely packed assemblies as the deposition progressed, confirming enhanced film coverage. Optical measurements highlighted significant modifications in the transparency and band structure of the films. The average optical transmittance in the visible range decreased progressively from 68% to 52% when deposition time was extended from 30 to 120 minutes, reflecting increased film density. Concurrently, the optical band gap narrowed from 3.27 eV to 3.22 eV. These findings demonstrate that single-step CBD provides a reliable and controllable route for synthesizing ZnO thin films with tunable physical properties.

The present work investigates the combined effect of precursor source and solvent on the structural, morphological, and optical properties of ZnO thin films prepared by the spin-coating technique. Three precursor sources (zinc acetate dihydrate, zinc chloride, and zinc nitrate hexahydrate) and four solvents (ethanol, 2-methoxyethanol, 2-propanol, and 1-methoxy-2-propanol) were systematically explored. X-ray diffraction analysis confirms that all films crystallize in the hexagonal wurtzite structure, with a pronounced (002) preferential orientation for zinc acetate-derived and most of the zinc chloride-derived films. Scanning electron microscopy reveals that both precursor and solvent strongly influence surface morphology. Zinc acetate yields smoother and more compact films, zinc chloride promotes larger hexagonal grains, and zinc nitrate leads to relatively porous structures. Among the solvents, 2-methoxyethanol produces the most uniform and dense films regardless of the precursor. Optical measurements show that transmittance is highly dependent on synthesis conditions, reaching up to 90% in the visible range for zinc acetate-based films, particularly with 2-methoxyethanol. The optical band gap varies between 3.20 and 3.37 eV, reflecting differences in crystallinity and defect density. Overall, these results highlight the key role of precursor–solvent interactions in tailoring ZnO thin film properties for optoelectronic applications.

The knowledge of the band alignment in semiconductor heterostructures is crucial, as it governs carrier confinement with many impacts on the performances of devices. By controlling the direction of the current flow in in-plane In_0.53Ga_0.47As/InP heterostructure nanowires, either horizontally along the nanowires or vertically into the InP substrate with low temperature multiple-probe tunneling spectroscopy, a direct measurement of the band offsets at the buried In_0.53Ga_0.47As/InP heterointerface is performed. Despite the unavoidable processing steps involved in selective area epitaxy, conduction and valence band offsets of 0.21 ± 0.01 and 0.40 ± 0.01 eV are, respectively, found, indicating the formation of an interface with a quality comparable to two-dimensional In_0.53Ga_0.47As/InP heterostructures.

This study investigates the crucial role of charge transport layers in enhancing the performance of inverted organic photovoltaic cells (OPVs) through advanced numerical simulations using OghmaNano software. OPVs offer distinct advantages, including lightweight, flexibility, and potential cost-effectiveness compared to traditional silicon-based counterparts, making them pivotal for sustainable energy solutions. We evaluate the efficiency of inverted (iOPVs) employing binary (PM6:L8-BO) and ternary (PM6:D18:L8-BO) active layers, utilizing electron transport layers (ETLs) including ZnO, TiO₂, and SnO₂, and hole transport layers (HTLs) such as MoO₃, PEDOT, and WO₃. Results highlight ZnO with a 15 nm-thick layer combined with MoO₃ HTL achieving an impressive efficiency of 18.89% in ternary devices, demonstrating the effectiveness of organic materials and ternary blends. The study demonstrates that TiO₂ or SnO₂ ETLs can compete effectively with ZnO ETLs, particularly when used at thinner thicknesses, and offers alternative fabrication methods. It suggests that employing thin ETL layers (15 ± 2 nm) could significantly enhance the performance of iOPV devices. Simulations are crucial for optimizing iOPV device configurations with thin ETL layers, enabling rapid prototyping and cost-effective exploration of material combinations and device architectures. These layers play a critical role in balancing charge carrier generation and transport efficiency, collectively maximizing device performance. Overall, the study underscores the pivotal role of simulations and optimized layer thicknesses in advancing OPV technology by refining manufacturing processes and accelerating the adoption of OPVs for sustainable energy solutions.