The successful transition of any nanocrystal-based product from the research phase to the commercial arena hinges on the ability to produce the required nanomaterial on large scales. The synthesis of ...colloidal nanocrystals using a heat-up (non-injection) method is a reliable means to achieve high quality nanomaterials on large scales with little or no batch-to-batch variation. In this class of synthesis precursors are heated within a reaction medium to induce a chemical reaction that yields monomer for nucleation and growth. Use of the heat-up technique circumvents the pitfalls of mixing time and poor heat management inherent to classical “hot-injection” methods. In heat-up syntheses monomer is produced in a more continuous fashion during the heating stage, making it more difficult to separate the nucleation and growth stages of the reaction, a factor that is conventionally considered detrimental toward achieving homogeneous colloidal dispersions. However, through the judicious selection of precursors, stabilizers, and reaction heating rates, these stages can be managed to yield colloids of comparable quality to those achieved via classical hot-injection methods. In this review we provide the reader with a fundamental basis upon which to understand the reaction requirements for achieving such favorable growth conditions. Given that the most important consideration in these reactions is precursor (and stabilizer) selection, we also provide an exposition of the precursor chemistry appropriate to achieving high quality products when using heat-up techniques. These topics form the foundation for critically evaluating the field of heat-up nanocrystal synthesis to date, including the synthesis of binary, ternary, and quaternary metal chalcogenide and pnictogenide nanocrystals, as well as metallic, metal oxide, and f-block conaining nanocrystals.
Plasmonic metal oxide nanocrystals bridge the optoelectronic gap between semiconductors and metals. In this study, we report a facile, non-injection synthesis of ZnO nanocrystals doped with Al, Ga, ...or In. The reaction readily permits dopant/zinc atomic ratios of over 15%, is amenable to high precursor concentrations (0.2 M and greater), and provides high reaction yields (>90%). The resulting colloidal dispersions exhibit high transparency in the visible spectrum and a wavelength-tunable infrared absorption, which arises from a dopant-induced surface plasmon resonance. Through a detailed investigation of reaction parameters, the reaction mechanism is fully characterized and correlated to the optical properties of the synthesized nanocrystals. The distinctive optical features of these doped nanocrystals are shown to be readily harnessed within thin films that are suitable for optoelectronic applications.
Inkjet printing (IJP) technology, adapted from home and office printing, has proven to be an essential research tool and industrial manufacturing technique in a wide range of printed electronic ...technologies, including optoelectronics. Its primary advantage over other deposition methods is the low‐cost and maskless on‐demand patterning, which offers unmatched freedom‐of‐design. Additional benefits include the efficient use of materials, contactless high‐resolution deposition, and scalability, enabling rapid translation of learning from small‐scale, laboratory‐based research into large‐scale industrial roll‐to‐roll manufacturing. In the development of organic solar cells (OSCs), IJP has enabled the printing of many of the multiple functional layers which comprise the complete cell as part of an additive printing scheme. Although IJP is only recently employed in perovskite solar cell (PeSC) fabrication, it is already showing great promise and is anticipated to find broader application with this class of materials. As OSCs and PeSCs share many common functional materials and device architectures, this review presents a progress report on the IJP of OSCs and PeSCs in order to facilitate knowledge transfer between the two technologies, with critical analyses of the challenges and opportunities also presented.
An environmentally friendly and scalable manufacturing method is essential for the successful commercialization of perovskite and organic solar cells. Inkjet printing is a roll‐to‐roll compatible technique which is demonstrated in lab to industrial scale production. Herein, the use of inkjet printing in perovskite and organic solar cells is reviewed together to facilitate knowledge exchange, as both technologies use similar materials and processes.
We report the synthesis of two new selenophene-containing ladder-type monomers, cyclopentadiselenophene (CPDS) and indacenodiselenophene (IDSe), via a 2-fold and 4-fold Pd-catalyzed coupling with a ...1,1-diborylmethane derivative. Copolymers with benzothiadiazole were prepared in high yield by Suzuki polymerization to afford materials which exhibited excellent solubility in a range of nonchlorinated solvents. The CPDS copolymer exhibited a band gap of just 1.18 eV, which is among the lowest reported for donor–acceptor polymers. Thin-film transistors were fabricated using environmentally benign, nonchlorinated solvents, with the CPDS and IDSe copolymers exhibiting hole mobility up to 0.15 and 6.4 cm2 V–1 s–1, respectively. This high performance was achieved without the undesirable peak in mobility often observed at low gate voltages due to parasitic contact resistance.
A new synthetic route, to prepare an alkylated indacenodithieno3,2‐bthiophene‐based nonfullerene acceptor (C8‐ITIC), is reported. Compared to the reported ITIC with phenylalkyl side chains, the new ...acceptor C8‐ITIC exhibits a reduction in the optical band gap, higher absorptivity, and an increased propensity to crystallize. Accordingly, blends with the donor polymer PBDB‐T exhibit a power conversion efficiency (PCE) up to 12.4%. Further improvements in efficiency are found upon backbone fluorination of the donor polymer to afford the novel material PFBDB‐T. The resulting blend with C8‐ITIC shows an impressive PCE up to 13.2% as a result of the higher open‐circuit voltage. Electroluminescence studies demonstrate that backbone fluorination reduces the energy loss of the blends, with PFBDB‐T/C8‐ITIC‐based cells exhibiting a small energy loss of 0.6 eV combined with a high JSC of 19.6 mA cm−2.
The synthesis of a novel alkylated indacenodithioeno3,2‐bthiophene (C8‐IDTT) based nonfullerene acceptor (C8‐ITIC), is reported. Compared to ITIC with phenylalkyl side chains, the acceptor exhibits a redshifted absorption with increased absorptivity. Solar cell power conversion efficiencies (PCEs) of up to 13.2 % are achieved, with the high PCE attributed to the broad absorption, high crystallinity of C8‐ITIC and low voltage loss.
Mixed organolead halide perovskites (MOHPs), CH3NH3Pb(BrxI1−x)3, have been shown to undergo phase segregation into iodide‐rich domains under illumination, which presents a major challenge to their ...development for photovoltaic and light‐emitting devices. Recent work suggested that phase‐segregated domains are localized at crystal boundaries, driving investigations into the role of edge structure and the growth of larger crystals with reduced surface area. Herein, a method for growing large (30×30×1 μm3) monocrystalline MAPb(BrxI1−x)3 single crystals is presented. The direct visualization of the growth of nanocluster‐like I‐rich domains throughout the entire crystal revealed that grain boundaries are not required for this transformation. Narrowband fluorescence imaging and time‐resolved spectroscopy provided new insight into the nature of the phase‐segregated domains and the collective impact on the optoelectronic properties.
Iodide‐rich clusters form and grow in the MAPb(BrxI1−x)3 single crystal under continuous light illumination. A combination of widefield microscopy and confocal microscopy provides detailed insight into phase segregation in individual MAPb(BrxI1−x)3 microplatelets.
Plasmonic biosensors based on noble metals generally suffer from low sensitivities if the perturbation of refractive‐index in the ambient is not significant. By contrast, the features of degenerately ...doped semiconductors offer new dimensions for plasmonic biosensing, by allowing charge‐based detection. Here, this concept is demonstrated in plasmonic hydrogen doped molybdenum oxides (HxMoO3), with the morphology of 2D nanodisks, using a representative enzymatic glucose sensing model. Based on the ultrahigh capacity of the molybdenum oxide nanodisks for accommodating H+, the plasmon resonance wavelengths of HxMoO3 are shifted into visible‐near‐infrared wavelengths. These plasmonic features alter significantly as a function of the intercalated H+ concentration. The facile H+ deintercalation out of HxMoO3 provides an exceptional sensitivity and fast kinetics to charge perturbations during enzymatic oxidation. The optimum sensing response is found at H1.55MoO3, achieving a detection limit of 2 × 10−9m at 410 nm, even when the biosensing platform is adapted into a light‐emitting diode‐photodetector setup. The performance is superior in comparison to all previously reported plasmonic enzymatic glucose sensors, providing a great opportunity in developing high performance biosensors.
HxMoO3 plasmonic disks are synthesized. H+ and concurrently electrons can be extracted from the host structure during a designed biochemical event. This alteration in charge rapidly changes the plasmon resonance features, hence creating an ultrasensitive platform.
A variety of deposition methods for two-dimensional crystals have been demonstrated; however, their wafer-scale deposition remains a challenge. Here we introduce a technique for depositing and ...patterning of wafer-scale two-dimensional metal chalcogenide compounds by transforming the native interfacial metal oxide layer of low melting point metal precursors (group III and IV) in liquid form. In an oxygen-containing atmosphere, these metals establish an atomically thin oxide layer in a self-limiting reaction. The layer increases the wettability of the liquid metal placed on oxygen-terminated substrates, leaving the thin oxide layer behind. In the case of liquid gallium, the oxide skin attaches exclusively to a substrate and is then sulfurized via a relatively low temperature process. By controlling the surface chemistry of the substrate, we produce large area two-dimensional semiconducting GaS of unit cell thickness (∼1.5 nm). The presented deposition and patterning method offers great commercial potential for wafer-scale processes.
We report that the inclusion of nonaromatic 5,5-dimethylcyclopentadiene monomer into a conjugated backbone is an attractive strategy to high performance semiconducting polymers. The use of this ...monomer enables a room temperature Suzuki copolymerization with a diketopyrrolopyrrole comonomer to afford a highly soluble, high molecular weight material. The resulting low band gap polymer exhibits excellent photo and thermal stability, and despite a large π–π stacking distance of 4.26 Å, it demonstrates excellent performance in thin-film transistor devices.
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