Nanostructured Architectures Research Articles

Progress of Cu2O/ZnO oxide heterojunction solar cells

Recent progress of low cost Cu2O/ZnO hetero-junction solar cells is reviewed in this paper. The Cu2O used as an absorbing layer in photovoltaic cells is a direct bandgap semiconductor, exhibiting natural p-type conductivity. The source material of Cu2O-based solar cells is abundant and environmentally friendly. The main device structure of Cu2O/ZnO solar cells presents a planar and nano-wire/nano-rod configuration. The nanostructured Cu2O architecture conduces to charge collection in the device. The planar Cu2O absorbing layer with large grain size, achieved through the thermal oxidation of Cu sheets, exhibits high quality of the Cu2O/ZnO solar cells. The interface buffer layer (like i-ZnO, a-ZTO and Ga2O3) and back surface field (BSF, such as p+-Cu2O) can effectively improve energy band alignment match and increase carrier transport. The Cu2O paired with a 10-nm-thick Ga2O3 layer provides a nearly ideal conduction band offset and thus reduces the interface recombination. The Ga2O3 is a highly suitable buffer layer for enhancing the Voc (Voc value reaches 1.2 V) and conversion efficiency of Cu2O-based solar cells. The p+-Cu2O like N-doped Cu2O (Cu2O:N) and Na-doped Cu2O (Cu2O:Na) can reduce back-contact resistance and create an electron-reflecting back surface field in the Cu2O based solar cells. When a p-type Cu2O: Na acts as an absorbing layer and a zinc-germanium-oxide (Zn1-xGex-O) thin film is used as an n-type layer (buffer), Cu2O hetero-junction solar cell with the device structure MgF2/Al-doped ZnO (ZnO:Al)/Zn0.38Ge0.62-O/Cu2O:Na shows an efficiency of 8.1%. The oxide hetero-junction solar cells have a great potential application in the future photovoltaic field.

Osteoinduction by Foamed and 3D-Printed Calcium Phosphate Scaffolds: Effect of Nanostructure and Pore Architecture.

Some biomaterials are osteoinductive, that is, they are able to trigger the osteogenic process by inducing the differentiation of mesenchymal stem cells to the osteogenic lineage. Although the underlying mechanism is still unclear, microporosity and specific surface area (SSA) have been identified as critical factors in material-associated osteoinduction. However, only sintered ceramics, which have a limited range of porosities and SSA, have been analyzed so far. In this work, we were able to extend these ranges to the nanoscale, through the foaming and 3D-printing of biomimetic calcium phosphates, thereby obtaining scaffolds with controlled micro- and nanoporosity and with tailored macropore architectures. Calcium-deficient hydroxyapatite (CDHA) scaffolds were evaluated after 6 and 12 weeks in an ectopic-implantation canine model and compared with two sintered ceramics, biphasic calcium phosphate and β-tricalcium phosphate. Only foams with spherical, concave macropores and not 3D-printed scaffolds with convex, prismatic macropores induced significant ectopic bone formation. Among them, biomimetic nanostructured CDHA produced the highest incidence of ectopic bone and accelerated bone formation when compared with conventional microstructured sintered calcium phosphates with the same macropore architecture. Moreover, they exhibited different bone formation patterns; in CDHA foams, the new ectopic bone progressively replaced the scaffold, whereas in sintered biphasic calcium phosphate scaffolds, bone was deposited on the surface of the material, progressively filling the pore space. In conclusion, this study demonstrates that the high reactivity of nanostructured biomimetic CDHA combined with a spherical, concave macroporosity allows the pushing of the osteoinduction potential beyond the limits of microstructured calcium phosphate ceramics.

Competitive amperometric immunosensor for determination of p53 protein in urine with carbon nanotubes/gold nanoparticles screen-printed electrodes: A potential rapid and noninvasive screening tool for early diagnosis of urinary tract carcinoma

Since p53 protein has become recognized biomarker for both diagnostic and therapeutic purposes in oncological diseases with particular relevance for bladder cancer, it is highly desirable to search for a novel sensing tool for detecting the patient's p53 level at the early stage. Here we report the first study on the development and validation of a novel disposable competitive amperometric immunosensor for determination of p53 protein at subnanomolar levels, based on p53 immobilization on gold nanoparticles/carbon nanotubes modified screen-printed carbon electrodes. The assay protocol requires the use of single anti-p53 mouse monoclonal antibody (DO-7 clone), able to recognize both wild-type and mutant p53. The developed immunosensor as well as the protocol of the electrochemical immunoassay were optimized by means of an experimental design procedure to assess the suitability of the device to be validated and applied for the determination of p53 in untreated and undiluted urine samples. It was found that the developed competitive immunodevice was able to achieve wide linear range detection of wild-type p53 from 20 pM to 10 nM with a low detection limit of 14 pM in synthetic urine samples, suggesting the sensor's capability of working in a complex sample matrix. The excellent performance results also in terms of selectivity, trueness and precision, coupled with the advantages of an easy preparation and low-cost assay in contrast to other methods which require very complex, time-consuming and costly nanostructured architectures, makes the developed competitive immunosensor an analytically robust diagnostic tool, valuable for implementation of screening and follow-up programs in patients with urologic malignancies.

(Invited) Towards High Cycle Efficiency of Si Based Negative Electrodes for Next Generation Lithium Ion Batteries

Si is an attractive negative electrode material for lithium ion batteries due to its high specific capacity (~3600 mAh/g). However, the huge volume swelling and shrinking during cycling leads to several coupled mechanical and chemical degradation at the material/electrode/cell level, including fracture of Si particles, unstable solid electrolyte interphase (SEI), and low Coulombic efficiency. In this talk, we will discuss how to improve the cycle efficiency from those aspects, starting with the fundamental understanding of the relationship between the structure and properties of SEI to pinpoint the SEI failure mechanisms using advanced in-situ electrochemical tools. Then we will discuss how to develop artificial SEI, combining the design of Si nanostructure and electrode architecture to enable the high cycle efficiency and the extended life. At last, we will discuss how the nanostructure design at material level can impact the electrochemical-mechanical behaviors at electrode and cell level and the trade-off between gravimetric energy density and volumetric energy density for EV applications.

Luminescence of a Transition Metal Complex Inside a Metamaterial Nanocavity.

Modification of the local density of optical states using metallic nanostructures leads to enhancement in the number of emitted quanta and photocatalytic turnover of luminescent materials. In this work, the fabrication of a metamaterial is presented that consists of a nanowire separated from a metallic mirror by a polymer thin film doped with a luminescent organometallic iridium(III) complex. The large spin-orbit coupling of the heavy metal atom results in an excited state with significant magnetic-dipole character. The nanostructured architecture supports two distinct optical modes and their assignment achieved with the assistance of numerical simulations. The simulations show that one mode is characterized by strong confinement of the electric field and the other by strong confinement of the magnetic field. These modes elicit drastic changes in the emitter's photophysical properties, including dominant nanocavity-derived modes observable in the emission spectra along with significant increases in emission intensity and the total decay rate. A combination of simulations and momentum-resolved spectroscopy helps explain the mechanism of the different interactions of each optical mode supported by the metamaterial with the excited state of the emitter.

Nanostructured Materials and Architectures for Advanced Infrared Photodetection

Infrared photodetectors are finding widespread applications in telecommunication, motion detection, chemical sensing, thermal imaging and bio‐medical imaging, etc. The nanostructured materials and architectures are attracting extensive interests in photodetectors in view of the potential benefits from confined light‐matter interaction, fast carrier dynamics and ultrahigh photoconductive gains. This review concentrates on the photodetection in the infrared spectrum and recent progresses in constructing advanced infrared photodetectors based on quantum wells, dots, and the rapidly evolving 1D and 2D materials are summarized. The recent achievements in exploring nanostructured plasmonic metamaterials for the intriguing subwavelength photon confinement and waveguides in devices are also surveyed considering their importance in device integration. An outlook of infrared photodetection is given in the end as a guideline for this vigorous field.

Sexual Dimorphism and Retinal Mosaic Diversification following the Evolution of a Violet Receptor in Butterflies.

Numerous animal lineages have expanded and diversified the opsin-based photoreceptors in their eyes underlying color vision behavior. However, the selective pressures giving rise to new photoreceptors and their spectral tuning remain mostly obscure. Previously, we identified a violet receptor (UV2) that is the result of a UV opsin gene duplication specific to Heliconius butterflies. At the same time the violet receptor evolved, Heliconius evolved UV-yellow coloration on their wings, due to the pigment 3-hydroxykynurenine (3-OHK) and the nanostructure architecture of the scale cells. In order to better understand the selective pressures giving rise to the violet receptor, we characterized opsin expression patterns using immunostaining (14 species) and RNA-Seq (18 species), and reconstructed evolutionary histories of visual traits in five major lineages within Heliconius and one species from the genus Eueides. Opsin expression patterns are hyperdiverse within Heliconius. We identified six unique retinal mosaics and three distinct forms of sexual dimorphism based on ommatidial types within the genus Heliconius. Additionally, phylogenetic analysis revealed independent losses of opsin expression, pseudogenization events, and relaxation of selection on UVRh2 in one lineage. Despite this diversity, the newly evolved violet receptor is retained across most species and sexes surveyed. Discriminability modeling of behaviorally preferred 3-OHK yellow wing coloration suggests that the violet receptor may facilitate Heliconius color vision in the context of conspecific recognition. Our observations give insights into the selective pressures underlying the origins of new visual receptors.

Interfacial phenomena between conjugated organic molecules and noble metals

Understanding interfacial interaction between conjugated organic molecules and noble metals is important not only for surface science, but also in relation to organic epitaxy, the architecture of intermolecular networks or nanostructures, and organic electronics. Particularly, properties of interfacial geometric and electronic structures and their related phenomena have attracted much interest for their potential in various electronic and optoelectronic applications, and thus extensive efforts have been devoted to understand and control organic/metal interfaces. We provide an overview of interfacial phenomena between conjugated organic molecules and noble metals via various interactions at the organic/metal interfaces such as surface-molecule and intermolecular interactions, as well as recent progress achieved in this area.

Block-Copolymer-Templated Hierarchical Porous Carbon Nanostructures with Nitrogen-Rich Functional Groups for Molecular Sensing.

The self-assembly of a block copolymer offers access to micellar nanodomains with tunable dimensions and structural diversity through control of such molecular parameters as the volume fraction and molecular mass. We fabricated hierarchical porous carbon (HPC) nanostructures with bundles of aggregated nanospheres and with nitrogen-rich functional groups through pyrolysis of diblock copolymer micelles in multiple layers. The resultant HPC nanostructures with a considerable specific surface area serve as an excellent substrate for surface-enhanced Raman spectroscopy (SERS), coupled with fluorescence quenching, for molecular sensing of physically adsorbed Rhodamine 6G. The abundant nitrogen atoms terminating on the surface of HPC nanostructures play a critical role in promoting a large Raman enhancement generated via a chemical mechanism. Most importantly, the observed enhancement factors show a clear dependence on the mesoscale porosity within HPC nanostructures, indicating that the chemical enhancement can be steadily tuned with control over the interfacial areas as a function of the nanosphere size. The unique architecture of HPC nanostructures based on the construction of a building block of a well-defined network of core-shell nanospheres provides a new design strategy for fabricating SERS substrates.

Eraser-based eco-friendly fabrication of a skin-like large-area matrix of flexible carbon nanotube strain and pressure sensors

This paper reports a new type of electronic, recoverable skin-like pressure and strain sensor, produced on a flexible, biodegradable pencil-eraser substrate and fabricated using a solvent-free, low-cost and energy efficient process. Multi-walled carbon nanotube (MWCNT) film, the strain sensing element, was patterned on pencil eraser with a rolling pin and a pre-compaction mechanical press. This induces high interfacial bonding between the MWCNTs and the eraser substrate, which enables the sensor to achieve recoverability under ambient conditions. The eraser serves as a substrate for strain sensing, as well as acting as a dielectric for capacitive pressure sensing, thereby eliminating the dielectric deposition step, which is crucial in capacitive-based pressure sensors. The strain sensing transduction mechanism is attributed to the tunneling effect, caused by the elastic behavior of the MWCNTs and the strong mechanical interlock between MWCNTs and the eraser substrate, which restricts slippage of MWCNTs on the eraser thereby minimizing hysteresis. The gauge factor of the strain sensor was calculated to be 2.4, which is comparable to and even better than most of the strain and pressure sensors fabricated with more complex designs and architectures. The sensitivity of the capacitive pressure sensor was found to be 0.135 MPa−1.To demonstrate the applicability of the sensor as artificial electronic skin, the sensor was assembled on various parts of the human body and corresponding movements and touch sensation were monitored. The entire fabrication process is scalable and can be integrated into large areas to map spatial pressure distributions. This low-cost, easily scalable MWCNT pin-rolled eraser-based pressure and strain sensor has huge potential in applications such as artificial e-skin in flexible electronics and medical diagnostics, in particular in surgery as it provides high spatial resolution without a complex nanostructure architecture.

Increase in graphitization and electrical conductivity of glassy carbon nanowires by rapid thermal annealing

Glassy carbon (GC) exhibits numerous desirable properties such as high thermal and chemical stabilities, good hardness, and good thermal and electrical conductivities. Moreover, GC can be manufactured into micro-/nanostructures through the versatile microfabrication technology, or carbon-micro electromechanical systems, which includes polymer patterning and pyrolysis. However, despite these advantages, there are growing demands for enhancing the electrical conductivity of GC, so that it can compensate or be substituted for other carbon allotropes such as graphite, carbon nanotubes, and graphene. In this study, we demonstrated that simple rapid thermal annealing (RTA) can dramatically enhance the electrical conductivity of pyrolyzed GC nanostructures by ∼ 300%. In this research, two different architectures of 1D carbon nanostructures such as a suspended nanowire that was separated from the substrate with a fixed distance and a substrate-bound nanowire were fabricated using conventional UV-lithography and pyrolysis processes, and their conductivity enhancement behaviors via RTA were studied. After the RTA process, the carbon/oxygen content and G-/D-band intensity ratios, which are correlated to the electrical conductivity, were enhanced, depending on the pyrolysis temperature. GC structures pyrolyzed at relatively low temperatures became more electrically conductive after the RTA process owing to their relatively higher oxygen content. This is because carbon atoms interconnected to oxygen atoms tend to align more readily than those corresponding to other carbon compositions because of the graphene healing mechanism. In addition, the architecture of the carbon nanostructures (i.e., whether they were suspended or substrate-bound nanowires) influenced the RTA-induced increase in electrical conductivity; the former showed a greater increase in electrical conductivity owing to its larger portion of well-aligned carbon atoms at the surface compared to the latter carbon structure. This is because graphitization is initiated on the surface and then proceeds to the carbon core in the heat treatment. In addition, tensile stress generated only at the suspended carbon nanowires during the pyrolysis process is assumed to enhance further the electrical conductivity via RTA. For instance, the electrical conductivity of the suspended carbon nanowires formed by pyrolysis at 600 °C was enhanced to ∼59,000 S/m after the RTA process.

Halogenation dictates the architecture of amyloid peptide nanostructures.

Amyloid peptides yield a plethora of interesting nanostructures though difficult to control. Here we report that depending on the number, position, and nature of the halogen atoms introduced into either one or both phenylalanine benzene rings of the amyloid β peptide-derived core-sequence KLVFF, four different architectures were obtained in a controlled manner. Our findings demonstrate that halogenation may develop as a general strategy to engineer amyloidal peptide self-assembly and obtain new amyloidal nanostructures.

Freestanding reduced graphene oxide-sulfur composite films for highly stable lithium-sulfur batteries.

Freestanding reduced graphene oxide-sulfur (rGO-S) composite films were fabricated by combining solution infiltration of sulfur into solvated rGO films with freeze-drying. Such rGO-S composite films can directly serve as the cathodes of lithium-sulfur (Li-S) batteries. The nanostructured architecture of rGO-S composite films considerably improved the cycling stability of Li-S batteries.

Probing the Crystal Structure and Formation Mechanism of Lanthanide-Doped Upconverting Nanocrystals

Lanthanide (Ln)-doped upconverting nanocrystals (UCNCs), such as NaLnF4 (with Ln = lanthanide), constitute an important class of nanoscale materials due to their capacity to convert near-infrared photons into near-ultraviolet or visible light. Although under intense investigation for more than a decade, UCNCs have been relatively underexplored especially regarding their crystal structure and mechanisms of formation in organic media. The former is needed to explain the relationship between atomic scale structure and upconversion (UC) properties of UCNCs (i.e., local symmetry for 4f–4f transition probability, Ln3+ distances for energy migration), while the latter is essential to finely tune the size, morphology, chemical composition, and architecture of well-defined upconverting nanostructures, which constitute the experimental levers to modify the optical properties. In this contribution, we use synchrotron-based diffraction experiments coupled to Rietveld and pair distribution function (PDF) analyses to u...

Biuret-assisted formation of nanostructured In2O3 architectures and their photoluminescence properties

Nanostructured indium oxide (In2O3) microcrystals were prepared by calcining hydrothermally synthesized indium hydroxide (In(OH)3) samples. A cubic structure and small crystallite sizes of the In2O3 microcrystals are determined from the X-ray diffraction (XRD) analysis. Observation of the scanning electron microscopy (SEM) shows that the crystalline morphology could be changed from micocubes, microrods to microspheres with appropriately control of the mole ratios of In3+ to biuret. Based on the SEM and FTIR analysis, a possible formation mechanism of In2O3 microcrystals with different morphologies is also proposed. The photoluminescence (PL) spectra show that the energy separation of the blue peaks at 2.85eV and 2.78eV corresponds to a phonon in sub band-gap energy levels of oxygen vacancies; and an ultraviolet peak near 3.22eV is observed, possibly originating from the longitudinal optical-phonon replica of the donor–acceptor pair transition.

A Flexible Nanostructured Paper of a Reduced Graphene Oxide-Sulfur Composite for High-Performance Lithium-Sulfur Batteries with Unconventional Configurations.

Flexible nanostructured reduced graphene oxide-sulfur (rGO-S) composite films are fabricated by synchronously reducing and assembling GO sheets with S nanoparticles on a metal surface. The nanostructured architecture in such composite films not only provides effective pathways for electron transport, but also suppresses the diffusion of polysulfides. Furthermore, they can serve as the cathodes of flexible Li-S batteries.

Strategy for enhancing the solar-driven water splitting performance of TiO2 nanorod arrays with thin Zn(O,S) passivated layer by atomic layer deposition

An array of one dimensional (1D) TiO2 nanorods (TONRs) has been regarded as an attractive candidate for electrochemical energy conversion and as storage device due to its large surface area, effiective light scattering, and undisturbed charge transport pathway. However, the high defect/trap densities on surface of the nanostructured morphology and architecture may generally hinder the performance enhancement by providing electron-hole recombination sites. Hence, the surface passivation of nanoarchitectures based photoelectrodes has recently received much attention as an effective strategy to enhance the charge-separation and charge-transfer processes in photoelectrochemical (PEC) water splitting devices. In particular, a coating layer with narrowing band gap materials can promote enhanced light harvesting in the UV–vis region as well as surface passivation, directly supplying a driving force for charge separation and charge transfer due to band alignment. In this paper, the surface of TONRs were passivated by 10 and 30nm thick Zn(O,S) layers with a relatively narrow band gap using an atomic layer deposition technique to modulate the thickness exactly. The 10nm Zn(O,S)/TONR array exhibits a significantly enhanced photocurrent density (Jsc) of 5.94mA/cm2 at 1.23eV vs NHE and an incident photon-to-electron conversion efficiency (IPCE) of 49% at 374nm compared with that of TONR arrays (Jsc of 1.99mA/cm2 at 1.23eV vs NHE and an IPCE of 20% at 380nm). However, the PEC performance is worse in the 30nm Zn(O,S)/TONR arrays, showing a Jsc of 3.09mA/cm2 at 1.23eV vs NHE and an IPCE of 29% at 374nm. To clearly demonstrate these PEC behaviors, the TONR and Zn(O,S)/TONR arrays were characterized by electrochemical impedance spectroscopy (EIS), open circuit voltage decay (OCV) measurement, and X-ray photoelectron spectroscopy (XPS). The above mentioned characterizations indicate that the enhanced PEC performance of the 10nm Zn(O,S)/TONR array resulted from the (i) increased light harvesting in the UV–vis region, (ii) lower charge transfer resistance and (iii) high value of valence band offset (VBO, −1.44eV) and conduction band offset (CBO, −1.2eV) than those of the TONR. However, the deterioration of Jsc in the 30nm Zn(O,S)/TONR array is attributed to the negative value of VBO (-0.13eV) and positive value of CBO (+0.27eV), as well as the higher charge transfer resistance to the electrolyte than that of the TONR arrays, despite of the improved light absorption in the visible region. The photocurrent densities of 10nm Zn(O,S)/TONR and 30nm Zn(O,S)/TONR photocathodes decay to 4.718mA/cm2 (5.90mA/cm2 at 0min) and 2.212mA/cm2 (3.03mA/cm2 at 0min) after 90min, respectively, they retain of about∼80% and 70% of its original values. These experimental results and discussions not only provide the physical insights into the surface passivation effect and band alignment but also can open a promising route to design the thin passivation layer having the narrowing band gap energy (1.0eV∼2.5eV) on the 1D TiO2 nanostructure for further enhanced performance and realization of a TiO2 based PEC system.

Zinc Oxide–Titania Heterojunction‐based Solid Nanospheres as Photoanodes for Electron‐Trapping in Dye‐Sensitized Solar Cells

AbstractAgile nanostructure architectures and smart combinations of semiconducting metal oxide materials are key features of high‐performing dye‐sensitized solar cells (DSSCs). Herein, we synthesize mesoporous solid nanospheres of ZnO–TiO2 with type‐II heterojunction and use these as an efficient photoanode material for excellent photoconversion. These polydisperse aggregates doped with 1 %, 5 %, and 10 % of ZnO exhibit improved solar cell performance with respect to pristine TiO2 under AM 1.5 G. The 1 % ZnO doped TiO2 nanosphere possess high specific surface area (84.23 m2 g−1) as a photoanode and shows high photoconversion efficiency of about 8.07 % with ca. 18 % improvement in the photocurrent density (Jsc) compare to TiO2 nanosphere. The improved solar cell performance (Δη=40 %) of ZnO decorated TiO2 nanospheres is ascribed to type‐II heterojunction of ZnO–TiO2, that reduces the electron recombination and synergistically enhances the electron mobility and charge collection capability.

Assessment of Nanostructured Carbons As Electrocatalyst Supports for Solid Acid Fuel Cells

Hydrogen fuel cells utilizing CsH2PO4 (CDP) as a solid proton conductor have tremendous promise as inexpensive devices for distributed generation. These systems known as solid acid fuel cells (SAFCs) demonstrate good activity for hydrogen oxidation and oxygen reduction, but require rather high platinum loadings. As part of an effort to decrease platinum content and increase platinum utilization we have developed a series of methodologies that use nanostructured carbons as a structure-directing electrode template. The current state-of-the-art SAFC utilizes thin films of platinum nanoparticles on a porous framework of CDP electrolyte.1 An enhancement in the platinum utilization, electrode surface area, and electrical interconnectivity may be best achieved by using carbon supports for the electrocatalyst and homogenizing framework with CDP. This approach should increase the number of catalytically active platinum sites for a given loading and may also allow for inclusion of nano-sized CDP particles, which will reduce the electrode overpotential. This reduction is due in part to an increase in the number of electrolyte-catalyst-gas triple-phase boundary points and should reduce the platinum loading in the electrocatalyst.We have investigated a variety of nanostructured carbon architectures including nanotubes and single-walled nanohorns2 as well as oxidized and surface functionalized derivatives of the above. The type of carbon support and its surface properties were shown to impart a pronounced effect on the fuel cell performance. We also propose a series of strategies to reduce the CDP particle size and increase surface area, thereby improving fuel cell performance and will discuss methods by which nanocomposite electrodes were created by infiltration of CDP into the pores or the interior of the carbons. The nature of the carbon nanostructure and the methodology employed to fabricate the composite electrodes was shown to dramatically impact the carbon corrosion during fuel cell operation. The loss of carbon by corrosion from the electrode will impact the electrical conductivity and may contribute to electrocatalyst nanoparticle coarsening. Developing a detailed understanding of these mechanisms and mitigation of the losses is an important consideration and as such we will suggest methodologies to ameliorate these effects. We will present a detailed structure-activity relationship using A.C. impedance spectroscopy, XRD, SEM, TEM, Raman microscopy, BET surface area, and measurements of proton conductivity. We also discuss how dispersion affects the homogeneity and percolation of the catalyst-CDP composites. Finally, we will discuss how functionalization of the nanostructured carbon materials affects the cell performance. (1) Papandrew, A. B.; Chisholm, C. R. I.; Elgammal, R. A.; Özer, M. M.; Zecevic, S. K. Chem. Mater. 2011, 23, 1659–1667. (2) Geohegan, D. B.; Puretzky, A. A.; Rouleau, C.; Jackson, J.; Eres, G.; Liu, Z.; Styers-Barnett, D.; Hu, H.; Zhao, B.; Ivanov, I. In Laser-Surface Interactions for New Materials Production: Tailoring Structure and Properties; Castillejo, M.; Ossi, P.; Zhigilei, L., Eds.; Springer Berlin Heidelberg, 2010; Vol. 130, pp. 1–17.

Towards nanostructured perovskite solar cells with enhanced efficiency: Coupled optical and electrical modeling

Third generation photovoltaic technologies based on perovskites have demonstrated an exceptional progress in solar energy conversion since their first use in 2009. Herein, we investigated the effect of using light trapping nanostructures on the absorption, carrier collection, and overall efficiency of perovskite (CH3NH3PbI3) solar cells using three dimensional (3D) finite element method (FEM) technique. A combined optical-electrical model was constructed to full characterize the proposed devices. Upon the use of nanotubular architecture, the optimized active area absorption enhanced by 6% and the total generation rate increased by 7% compared to the planar architecture. Under one sunlight illumination (AM1.5G), with normal incident angle, the solar cells containing nanostructured light trapping architecture showed a drastic enhancement in the short circuit current (Jsc), the quantum efficiency (EQE), and the overall efficiency compared to the planar film-based solar cell. The obtained enhancements would open a new route for integrating light trapping nanostructures in CH3NH3PbI3 perovskite-based solar cells for better efficiency.