The pursuit of high-performance, lead-free optoelectronic materials has led to significant advances in semiconductors containing lone-pair ns² cations, where structural dimensionality plays a pivotal role in determining electronic properties and device performance. This review systematically examines these materials across different dimensionalities—3D, 2D, 1D, and 0D—highlighting how spatial confinement governs band structure, carrier mobility, defect behavior, and application potential.
In three-dimensional (3D) systems, tin- and germanium-based halide perovskites such as FASnI₃ and CsGeI₃ offer direct bandgaps (~1.4–1.6 eV) suitable for photovoltaics. FASnI₃ achieves a certified power conversion efficiency (PCE) of up to 11.22% through surface passivation with n-propylammonium iodide, which suppresses trap states. However, the facile oxidation of Sn²⁺ to Sn⁴⁺ remains a major challenge. Strategies like two-step synthesis, hydrazine-based reduction, and cation mixing have significantly improved film quality, enabling record carrier lifetimes exceeding 3.87 ns and PCEs nearing 12%. Germanium analogs, while theoretically promising with balanced effective masses and high dielectric constants, suffer from rapid Ge²⁺ oxidation, limiting practical implementation.
Two-dimensional (2D) materials exhibit enhanced stability and tunable optoelectronic properties due to quantum confinement and layered structures. Tin/germanium monochalcogenides like SnS and GeSe display quasidirect bandgaps (~1.1–1.2 eV), high carrier mobilities (up to 128.6 cm² V⁻¹ s⁻¹ for GeSe), and strong absorption coefficients (>10⁵ cm⁻¹). Devices based on GeSe nanosheets achieve a solar cell efficiency of 5.2%, while heterojunctions with MoS₂ enable broadband photodetection with responsivity reaching 3.5 × 10⁴ A W⁻¹. Bismuth iodide (BiI₃), with its layered rhombohedral structure, exhibits high resistivity (10⁹ Ω·cm) and a bandgap of 1.67 eV, making it ideal for radiation detection. Vertical nanoplates of BiI₃ achieve specific detectivity of 1.65 × 10¹² Jones and fast response times (3/9 ms), rivaling conventional 2D materials.
Metal pnictide chalcogenides (APnE₂, e.g., AgBiS₂) represent another class of 2D candidates. AgBiS₂ films synthesized via solution processing reach a certified PCE of 6.3%, benefiting from high absorption and favorable band alignment. By modifying surface-to-volume ratios and introducing doping agents, carrier mobility can be enhanced, pushing efficiency to 6.4%. Similarly, bismuth oxyhalides (BiOX) possess layered Matlockite structures that generate internal electric fields, promoting charge separation. Nanostructured BiOCl and BiOI show exceptional photocatalytic activity, with hierarchical BiOI microspheres achieving hydrogen evolution rates of 1316.9 µmol h⁻¹ g⁻¹ under visible light.
One-dimensional (1D) materials, such as Sb₂S₃ and Bi₂S₃ ribbons, exhibit extreme anisotropy in carrier transport. Conductivity along the ribbon axis is orders of magnitude higher than perpendicular to it, enabling directional charge flow. High-quality Sb₂(S,Se)₃ films grown in favorable orientations yield solar cells with a certified efficiency of 10%, second only to lead perovskites. Incorporating Cu-doped grain boundaries creates built-in electric fields that suppress recombination, boosting efficiency to 7.04%. These materials also serve as sensitive photodiodes, with EQEs exceeding 83%.
Zero-dimensional (0D) A₃M₂X₉ perovskites, including Cs₃Bi₂I₉ and MA₃Sb₂I₉, feature isolated [M₂X₉]³⁻ dimers that prevent ion migration and enhance long-term stability.TMEM100 Antibody Epigenetic Reader Domain Despite indirect bandgaps (~2.HTRA1 Antibody supplier 2–2.PMID:35018701 4 eV), they demonstrate strong excitonic behavior and high resistivity. Device integration using hybrid interfaces—such as Cs₃Bi₂I₉–Ag₃Bi₂I₉ heterojunctions—achieves a record PCE of 3.6% and VOC of 0.89 V. X-ray detectors based on these materials show low detection limits (55 nGyair s⁻¹) and high sensitivity (8.2 × 10³ µC Gy⁻¹ cm⁻²).
Across all dimensionalities, key challenges remain: deep-level traps in low-dimensional systems, interfacial recombination, and inefficient charge extraction. Future progress depends on rational design strategies—including compositional engineering, defect passivation, and interface optimization—to overcome these limitations. The dimensionality principle not only guides material selection but also enables precise control over bandgaps, carrier dynamics, and functional versatility, paving the way for next-generation sustainable optoelectronics beyond lead-based perovskites.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com
