Extended shortwave infrared (eSWIR) photodetectors that employ solution‐processable semiconductors have attracted attention for use in applications such as ranging, night vision, and gas detection. Colloidal quantum dots (CQDs) are promising materials with facile bandgap tunability across the visible‐to‐mid‐infrared wavelengths. However, toxic elements, such as Hg and Pb, and the slow response time of CQD‐based IR photodetectors, limit their commercial viability. This article presents a novel eSWIR photodetector that is fabricated using silver telluride (Ag₂Te) CQDs. Effective thiolate ligand exchange enables a lower trap density and improved carrier mobility in CQD solids. Furthermore, a vertical p‐n photodiode architecture with a favorable energy‐level landscape is utilized to facilitate charge extraction, resulting in a fast, room‐temperature‐operable, and toxic‐element‐free CQD photodetector. The best eSWIR Ag₂Te CQD photodetector exhibits a fall time of 72 ns, representing the fastest response time among all prior CQD‐based eSWIR photodetectors, including those containing toxic elements, such as Pb and Hg.

The fabrication of heterostructures via solution process is one of the essential technologies for realizing efficient advanced-generation optoelectronics. Hybrid structures comprising colloidal quantum dots (CQD) and organic semiconducting molecules are garnering considerable research interest because of their complementing optical and electrical properties. However, blending both the materials and forming a stable electronic ink are a challenge owing to the solubility mismatch. Herein, a CQD:organic ternary-blended hybrid solar ink is devised, and efficient hybrid solar cells are demonstrated via single-step spin coating under ambient conditions. Specifically, the passivation of the benzoic acid ligand on the CQD surface enables the dissolution in low-polar solvent such as chlorobenzene, which yields a stable CQD:organic hybrid ink. The hybrid ink facilitates the formation of favorable thin-film morphologies and, consequently, improves the charge extraction efficiency of the solar cells. The resulting hybrid solar cells exhibit a power conversion efficiency of 15.24 that is the highest performance among all existing air-processed CQD:organic hybrid solar cells.

Since the kerfless wafer method for manufacturing multicrystalline silicon (mc-Si) wafers does not involve a sawing process, there occurs no saw damage on the surface, and the product is characterized by a flat surface morphology. These wafers cannot be effectively textured under the conditions of a conventional acidic etching solution with stability or efficiency because the surfaces are free of the surface damage caused by sawing. The texturing process developed in this article uses a conventional acidic etching solution without additives and a metal catalyst; the resulting process is a novel double acidic texturing (DAT) process capable of texturing using hydrofluoric acid (HF), HNO $_{3}$ , CH $_{3}$ COOH, and deionized water. The kerfless wafers treated with this novel texturing treatment had a weighted average reflectance (R $_{w}$ ) of 25.40%, which is ∼5.76% less than that of kerfless wafers textured under conventional acidic texturing conditions (R $_{w}$ = ∼31.16%). A solar cell manufactured with the new DAT process showed an enhanced short-circuit current density (+2.65 mA·cm−2), fill factor (+3.87%), and efficiency (+2.18%) than those of a cell fabricated without using this novel double treatment.

Crystalline solar cells have attracted significant attention in the solar-cell market owing to their low material cost. Multicrystalline silicon (mc-Si) is usually fabricated using the casting method, and approximately 35% of Si is removed as kerf in the sawing process performed to fabricate the wafer. The fabrication of kerfless mc-Si wafers does not involve the sawing and growing process. Hence, there is a significant reduction in the process cost (∼50%), while saving ∼66% energy in wafer manufacturing. Moreover, the absence of sawing process will result in no surface damage and smoother surfaces. Texturing using conventional methods such as acidic chemical etching are ineffective and as a result, the desired surface texture cannot be obtained. To solve this problem, the texture can be created using relatively expensive and complicated processes such as reactive-ion etching or metal-catalyzed chemical etching, which are not affected by the shape of the wafer surface. This article proposes a method for creating an effective texture that can increase the light absorptivity of mc-Si wafers manufactured by the kerfless method with no surface damage. This technology is a cost-effective and reliable process that uses an acidic chemical solution with no additive or mask. The etching rate and texture shape are investigated for different solution ratios of HF and HNO $_3$ . The surface morphology is examined using scanning electron microscopy, and the reflectance at 300–1200 nm is measured using ultraviolet–visible spectroscopy. A weighted average reflectance of ∼20.0% is obtained, which reduces to ∼7.4% on depositing an antireflective film.

Colloidal quantum dots (CQDs) are promising semiconductors for optoelectronic applications owing to their bandgap tunability and solution processability. Historically, ethanedithiol has been widely employed as a surface ligand to form a p‐type CQD layer via a layer‐by‐layer process. However, the limited control of p‐type characteristics reduces the device performance, and the high reactivity of ligand and processing solvents degrade the underlying layer. In this study, a thiol‐free p‐type CQD is demonstrated by creating native p‐type CQDs during the synthesis process. Sulfurization of PbS CQD results in p‐type properties that enable the avoidance of any further thiol‐ligand treatment process. Further, alternative surface passivation of the sulfurized CQD using halide ligand yields a robust, p‐type, morphologically uniform, and trap‐suppressed film. The developed CQD film is then employed as a hole‐transporting layer (HTL) for both broadband solar cells and photodetectors. The resulting CQD devices exhibit improved performance with a 65.7% increase in photovoltaic efficiency and a 1.7‐fold improvement in responsivity for infrared photodetection. The devices also demonstrate higher ambient stability, retaining 85% of the initial performance after 1,000 hr owing to the uniform top HTL morphology, indicating the potential of the new p‐type layer to be utilized in various emerging optoelectronics.