ABSTRACT A photoanode protection strategy using a multifunctional NiOx coating is presented. The ... more ABSTRACT A photoanode protection strategy using a multifunctional NiOx coating is presented. The transparency/antireflectivity, low electrochromism, conduction of holes, corrosion protection, and active electrocatalysis for water-oxidation half-reaction are described.
We discuss `full spectrum' photovoltaic modules that leverage low-cost III-V compound semicon... more We discuss `full spectrum' photovoltaic modules that leverage low-cost III-V compound semiconductor cells, efficient optics and unconventional fabrication/assembly methods, and discuss advances in photoelectrochemical water-splitting with high efficiency.
Global climate change coupled with increasing global energy consumption drives the need for renew... more Global climate change coupled with increasing global energy consumption drives the need for renewable and carbon-neutral alternatives to fossil fuels. Photoelectrochemical devices store solar energy in chemical bonds, and have the potential to provide cost-effective fuel for grid-scale energy storage as well as to serve as a feedstock for the production of carbon-neutral transportation fuels. A widely recognized goal is the demonstration of a monolithically-integrated solar-fuels system that is simultaneously efficient, stable, intrinsically safe, and scalably manufacturable. This thesis presents the development of three separate high-efficiency solar fuel devices protected by thin films of amorphous TiO2, and develops light management strategies to increase the performance of these devices. First, high-efficiency monolithic cells were designed to perform solar water-splitting and CO2 reduction. These designs are driven by high-quality single-crystalline III-V semiconductors that ar...
Technol. important small band gap (< 2 eV) semiconductors must be stabilized against corrosion... more Technol. important small band gap (< 2 eV) semiconductors must be stabilized against corrosion or passivation in aq. electrolytes before they can be used as photoelectrodes that directly produce fuels from sunlight. In addn., incorporation of electrocatalysts on the surface of the photoelectrodes is required for efficient oxidn. of H_2O to O_2(g) and redn. of H_2O or H_2O and CO_2 to fuels. Stabilization of technol. important semiconductors against photocorrosion and photopassivation would have a significant impact on photoelectrochem. energy conversion, and could enable the development of a new generation of robust integrated devices for efficient solar-driven water splitting and solar-driven CO_2 redn. Previous efforts have been extensively dedicated on elongating the lifetime of semiconductors under harsh fuel forming reaction conditions esp. during the water oxidn. half reaction. To date, the energy conversion performances and stability were limited on these systems, obscurin...
Fifteenth Conference on Education and Training in Optics and Photonics: ETOP 2019, 2019
A modular laboratory curriculum with exercises for students and lesson plans for teachers is pres... more A modular laboratory curriculum with exercises for students and lesson plans for teachers is presented. Fundamentals of basic integrated photonic (IP) devices can be taught, first as a lecture-in-the-lab followed by “hands-on” laboratory measurements. This comprehensive curriculum utilizes data collected from the “AIM Photonics Institute PIC education chip” that was designed specifically for the purpose of education, and was fabricated at AIM SUNY Poly. Training using this modular curriculum will be performed through the AIM Photonics Academy network in New York (NY) and Massachusetts (MA), either as a full semester course or as a condensed boot-camp. A synergistic development and delivery of this curriculum will coherently leverage multiple resources across the network and can serve as a model for education and workforce development in other Manufacturing USA institutes, as well as for overseas partners.
Fifteenth Conference on Education and Training in Optics and Photonics: ETOP 2019, Jul 2, 2019
Silicon-based photonics is mobilizing into a manufacturing industry with specialized integrated c... more Silicon-based photonics is mobilizing into a manufacturing industry with specialized integrated circuit design requirements for applications in low power cloud computing, high speed wireless, smart sensing, and augmented imaging. The AIM Photonics Manufacturing USA Institute, which operates the world's most advanced 300mm semiconductor research fab, has co-developed a Process Design Kit (PDK) in fabless circuit design for these expanding digital and analog applications; however, there currently isn't available an in-depth curriculum to train engineers (academia, industry) in the AIM PDK process and Electronic Photonic Design Automation (EPDA) software. AIM Photonics Academy, an education initiative of AIM Photonics based at MIT, has collaborated with faculty to create three online MOOC edX courses that (1) introduce integrated photonics devices, and applications performance needs and metrics; and (2) train into the AIM PDK and specialized EPDA tools in a six week design project to lay out an application-specific photonic transceiver. The courses are structured around asynchronous video lectures and exploratory design problems that involve Python and Matlab-based first-principles calculations (systems modeling) or advanced EPDA tools (circuit design and layout). The online MOOC courses can optionally form a tandem blended learning component with two AIM Photonics Academy on-site training programs: the annual AIM Summer Academy one-week intensive program (held every July at MIT), or a photonic integrated circuit testing workshop (the first workshop is planned for fall 2019). These courses are a cornerstone effort at AIM to found and support a specialized cohort community of future integrated photonics designers.
Fifteenth Conference on Education and Training in Optics and Photonics: ETOP 2019, Jul 2, 2019
There is large industry demand for qualified engineers and technicians in photonics advanced manu... more There is large industry demand for qualified engineers and technicians in photonics advanced manufacturing. Current workforce training methods require expensive state-of-the-art laboratory equipment, as well as commercial licenses for photonic design software, which can be prohibitively costly for many universities. Virtual laboratories and Massive Open Online Courses (MOOCs) can help fill this training gap by providing a scalable approach to photonics workforce education for an international audience. In this project, AIM Photonics Academy-the education initiative of AIM Photonics, a Manufacturing USA Institute-is creating a virtual laboratory to enable self-directed learning for the emerging photonics workforce. Students learn photonic device and circuit modeling in a 3D online virtual lab environment with interactive simulations of micron-scale photonic visualizations. An intuitive interface highlights the most critical device design parameters and their optimal operational settings for applications in Datacom, wireless communication, sensing, and imaging. Simulations include silicon waveguide propagation and loss, radial waveguide bends, and directional couplers for photonic integrated circuits (PICs). In spring of 2019, AIM Academy has integrated these simulations into an online course focused on PIC-chip design, with a fundamentals course expected in fall of 2019. Additionally, these online tools will be used in a blended learning curriculum in 2020 to train engineers and technicians in semiconductor design, testing and packaging for photonics applications. Following online module completion, students can take blended learning on-site workshops at affiliated university laboratories to capitalize on their simulated training with hands-on experiments in chip design, packaging, and optical or electrical testing.
Recently, a photoelectrode protection strategy, which uses an amorphous “leaky” TiO2 coating to f... more Recently, a photoelectrode protection strategy, which uses an amorphous “leaky” TiO2 coating to form a complex semiconductor/TiO2/Ni structure, has shown to stabilize semiconductor-solution interfaces against photoanodic corrosion. Particularly, stabilizing semiconductor-aqueous solution interfaces for water oxidation is important because water oxidation is required for all solar fuel strategies, e.g. H2 production and CO2 reduction. We show that this TiO2protection strategy has stabilized a number of 1.1 – 1.9 eV band gap light absorbers including Si, group III-V, group II-VI semiconductors, their tandem structures and wire structures for up to 2000 hours continuous water oxidation in 1 M KOH(aq). Because of this, various otherwise unstable materials can be brought back to the table again for building photoelectrochemical devices. A water splitting reactor prototype of ~10% solar-to-hydrogen efficiency was also built. The n-doped Si/TiO2/Ni structure also operates as a high...
The photoelectrochemical conversion of sunlight into gaseous hydrogen or liquid hydrocarbon fuels... more The photoelectrochemical conversion of sunlight into gaseous hydrogen or liquid hydrocarbon fuels can be an efficient method for renewable energy production, but significant materials challenges hinder the fabrication of integrated devices that are both efficient and stable. In particular, many moderate band gap semiconductors (Eg = 1-2 eV) photocorrode rapidly (within seconds or minutes) during electrochemical operation in aqueous solution. This process is exacerbated in water oxidation photoanodes that operate at high potentials in acidic or alkaline environments. The stable and reliable use of moderate band gap semiconductors is integral to JCAP’s mission of creating efficient solar-to-fuels devices. As such, recent work at JCAP has focused on developing thin films that protect a number of high-efficiency semiconductors, including Si, CdTe, and GaP. Such protection layers need to satisfy a number of requirements: they must resist corrosion in alkaline or acidic environments, they...
A monolithically integrated device, protected by a TiO2 stabilization layer, splits water using s... more A monolithically integrated device, protected by a TiO2 stabilization layer, splits water using sunlight.
A photoanode protection strategy using a multifunctional NiOx coating is presented. The transpare... more A photoanode protection strategy using a multifunctional NiOx coating is presented. The transparency/antireflectivity, low electrochromism, conduction of holes, corrosion protection, and active electrocatalysis for water-oxidation half-reaction are described.
Films of CoP have been electrochemically synthesized, characterized, and evaluated for performanc... more Films of CoP have been electrochemically synthesized, characterized, and evaluated for performance as a catalyst for the hydrogen-evolution reaction (HER). The film was synthesized by cathodic deposition from a boric acid solution of Co 2+ and H 2 PO 2 − on copper substrates followed by operando remediation of exogenous contaminants. The films were characterized structurally and compositionally by scanning-electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Raman spectrophotometry. The catalytic activity was evaluated by cyclic voltammetry and chronopotentiometry. Surface characterization prior to electrocatalysis indicated that the film consisted of micrometer-sized spherical clusters located randomly and loosely on a slightly roughened surface. The composition of both the clusters and surface consisted of cobalt in the metallic, phosphide, and amorphous-oxide forms (CoO• Co 2 O 3) and of phosphorus as phosphide and orthophosphate. The orthophosphate species, produced by air-oxidation, were eliminated upon HER electrocatalysis in sulfuric acid. The operando film purification yielded a functional electrocatalyst with a Co:P stoichiometric ratio of 1:1. After the HER, the surface was densely packed with micrometer-sized, mesa-like particles whose tops were flat and smooth. The CoP eletrodeposit exhibited an 85 mV overvoltage (η) for the HER at a current density of 10 mA cm −2 and was stable under operation in highly acidic solution, with an increase in η of 18 mV after 24 h of continuous operation. The comparative HER catalytic performance of CoP, film or nanoparticles, is as follows: η Pt < η CoP film = η CoP NP , η Ni 2 P < η CoSe 2 < η MoS 2 < η MoSe 2 .
ABSTRACT A photoanode protection strategy using a multifunctional NiOx coating is presented. The ... more ABSTRACT A photoanode protection strategy using a multifunctional NiOx coating is presented. The transparency/antireflectivity, low electrochromism, conduction of holes, corrosion protection, and active electrocatalysis for water-oxidation half-reaction are described.
We discuss `full spectrum' photovoltaic modules that leverage low-cost III-V compound semicon... more We discuss `full spectrum' photovoltaic modules that leverage low-cost III-V compound semiconductor cells, efficient optics and unconventional fabrication/assembly methods, and discuss advances in photoelectrochemical water-splitting with high efficiency.
Global climate change coupled with increasing global energy consumption drives the need for renew... more Global climate change coupled with increasing global energy consumption drives the need for renewable and carbon-neutral alternatives to fossil fuels. Photoelectrochemical devices store solar energy in chemical bonds, and have the potential to provide cost-effective fuel for grid-scale energy storage as well as to serve as a feedstock for the production of carbon-neutral transportation fuels. A widely recognized goal is the demonstration of a monolithically-integrated solar-fuels system that is simultaneously efficient, stable, intrinsically safe, and scalably manufacturable. This thesis presents the development of three separate high-efficiency solar fuel devices protected by thin films of amorphous TiO2, and develops light management strategies to increase the performance of these devices. First, high-efficiency monolithic cells were designed to perform solar water-splitting and CO2 reduction. These designs are driven by high-quality single-crystalline III-V semiconductors that ar...
Technol. important small band gap (< 2 eV) semiconductors must be stabilized against corrosion... more Technol. important small band gap (< 2 eV) semiconductors must be stabilized against corrosion or passivation in aq. electrolytes before they can be used as photoelectrodes that directly produce fuels from sunlight. In addn., incorporation of electrocatalysts on the surface of the photoelectrodes is required for efficient oxidn. of H_2O to O_2(g) and redn. of H_2O or H_2O and CO_2 to fuels. Stabilization of technol. important semiconductors against photocorrosion and photopassivation would have a significant impact on photoelectrochem. energy conversion, and could enable the development of a new generation of robust integrated devices for efficient solar-driven water splitting and solar-driven CO_2 redn. Previous efforts have been extensively dedicated on elongating the lifetime of semiconductors under harsh fuel forming reaction conditions esp. during the water oxidn. half reaction. To date, the energy conversion performances and stability were limited on these systems, obscurin...
Fifteenth Conference on Education and Training in Optics and Photonics: ETOP 2019, 2019
A modular laboratory curriculum with exercises for students and lesson plans for teachers is pres... more A modular laboratory curriculum with exercises for students and lesson plans for teachers is presented. Fundamentals of basic integrated photonic (IP) devices can be taught, first as a lecture-in-the-lab followed by “hands-on” laboratory measurements. This comprehensive curriculum utilizes data collected from the “AIM Photonics Institute PIC education chip” that was designed specifically for the purpose of education, and was fabricated at AIM SUNY Poly. Training using this modular curriculum will be performed through the AIM Photonics Academy network in New York (NY) and Massachusetts (MA), either as a full semester course or as a condensed boot-camp. A synergistic development and delivery of this curriculum will coherently leverage multiple resources across the network and can serve as a model for education and workforce development in other Manufacturing USA institutes, as well as for overseas partners.
Fifteenth Conference on Education and Training in Optics and Photonics: ETOP 2019, Jul 2, 2019
Silicon-based photonics is mobilizing into a manufacturing industry with specialized integrated c... more Silicon-based photonics is mobilizing into a manufacturing industry with specialized integrated circuit design requirements for applications in low power cloud computing, high speed wireless, smart sensing, and augmented imaging. The AIM Photonics Manufacturing USA Institute, which operates the world's most advanced 300mm semiconductor research fab, has co-developed a Process Design Kit (PDK) in fabless circuit design for these expanding digital and analog applications; however, there currently isn't available an in-depth curriculum to train engineers (academia, industry) in the AIM PDK process and Electronic Photonic Design Automation (EPDA) software. AIM Photonics Academy, an education initiative of AIM Photonics based at MIT, has collaborated with faculty to create three online MOOC edX courses that (1) introduce integrated photonics devices, and applications performance needs and metrics; and (2) train into the AIM PDK and specialized EPDA tools in a six week design project to lay out an application-specific photonic transceiver. The courses are structured around asynchronous video lectures and exploratory design problems that involve Python and Matlab-based first-principles calculations (systems modeling) or advanced EPDA tools (circuit design and layout). The online MOOC courses can optionally form a tandem blended learning component with two AIM Photonics Academy on-site training programs: the annual AIM Summer Academy one-week intensive program (held every July at MIT), or a photonic integrated circuit testing workshop (the first workshop is planned for fall 2019). These courses are a cornerstone effort at AIM to found and support a specialized cohort community of future integrated photonics designers.
Fifteenth Conference on Education and Training in Optics and Photonics: ETOP 2019, Jul 2, 2019
There is large industry demand for qualified engineers and technicians in photonics advanced manu... more There is large industry demand for qualified engineers and technicians in photonics advanced manufacturing. Current workforce training methods require expensive state-of-the-art laboratory equipment, as well as commercial licenses for photonic design software, which can be prohibitively costly for many universities. Virtual laboratories and Massive Open Online Courses (MOOCs) can help fill this training gap by providing a scalable approach to photonics workforce education for an international audience. In this project, AIM Photonics Academy-the education initiative of AIM Photonics, a Manufacturing USA Institute-is creating a virtual laboratory to enable self-directed learning for the emerging photonics workforce. Students learn photonic device and circuit modeling in a 3D online virtual lab environment with interactive simulations of micron-scale photonic visualizations. An intuitive interface highlights the most critical device design parameters and their optimal operational settings for applications in Datacom, wireless communication, sensing, and imaging. Simulations include silicon waveguide propagation and loss, radial waveguide bends, and directional couplers for photonic integrated circuits (PICs). In spring of 2019, AIM Academy has integrated these simulations into an online course focused on PIC-chip design, with a fundamentals course expected in fall of 2019. Additionally, these online tools will be used in a blended learning curriculum in 2020 to train engineers and technicians in semiconductor design, testing and packaging for photonics applications. Following online module completion, students can take blended learning on-site workshops at affiliated university laboratories to capitalize on their simulated training with hands-on experiments in chip design, packaging, and optical or electrical testing.
Recently, a photoelectrode protection strategy, which uses an amorphous “leaky” TiO2 coating to f... more Recently, a photoelectrode protection strategy, which uses an amorphous “leaky” TiO2 coating to form a complex semiconductor/TiO2/Ni structure, has shown to stabilize semiconductor-solution interfaces against photoanodic corrosion. Particularly, stabilizing semiconductor-aqueous solution interfaces for water oxidation is important because water oxidation is required for all solar fuel strategies, e.g. H2 production and CO2 reduction. We show that this TiO2protection strategy has stabilized a number of 1.1 – 1.9 eV band gap light absorbers including Si, group III-V, group II-VI semiconductors, their tandem structures and wire structures for up to 2000 hours continuous water oxidation in 1 M KOH(aq). Because of this, various otherwise unstable materials can be brought back to the table again for building photoelectrochemical devices. A water splitting reactor prototype of ~10% solar-to-hydrogen efficiency was also built. The n-doped Si/TiO2/Ni structure also operates as a high...
The photoelectrochemical conversion of sunlight into gaseous hydrogen or liquid hydrocarbon fuels... more The photoelectrochemical conversion of sunlight into gaseous hydrogen or liquid hydrocarbon fuels can be an efficient method for renewable energy production, but significant materials challenges hinder the fabrication of integrated devices that are both efficient and stable. In particular, many moderate band gap semiconductors (Eg = 1-2 eV) photocorrode rapidly (within seconds or minutes) during electrochemical operation in aqueous solution. This process is exacerbated in water oxidation photoanodes that operate at high potentials in acidic or alkaline environments. The stable and reliable use of moderate band gap semiconductors is integral to JCAP’s mission of creating efficient solar-to-fuels devices. As such, recent work at JCAP has focused on developing thin films that protect a number of high-efficiency semiconductors, including Si, CdTe, and GaP. Such protection layers need to satisfy a number of requirements: they must resist corrosion in alkaline or acidic environments, they...
A monolithically integrated device, protected by a TiO2 stabilization layer, splits water using s... more A monolithically integrated device, protected by a TiO2 stabilization layer, splits water using sunlight.
A photoanode protection strategy using a multifunctional NiOx coating is presented. The transpare... more A photoanode protection strategy using a multifunctional NiOx coating is presented. The transparency/antireflectivity, low electrochromism, conduction of holes, corrosion protection, and active electrocatalysis for water-oxidation half-reaction are described.
Films of CoP have been electrochemically synthesized, characterized, and evaluated for performanc... more Films of CoP have been electrochemically synthesized, characterized, and evaluated for performance as a catalyst for the hydrogen-evolution reaction (HER). The film was synthesized by cathodic deposition from a boric acid solution of Co 2+ and H 2 PO 2 − on copper substrates followed by operando remediation of exogenous contaminants. The films were characterized structurally and compositionally by scanning-electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Raman spectrophotometry. The catalytic activity was evaluated by cyclic voltammetry and chronopotentiometry. Surface characterization prior to electrocatalysis indicated that the film consisted of micrometer-sized spherical clusters located randomly and loosely on a slightly roughened surface. The composition of both the clusters and surface consisted of cobalt in the metallic, phosphide, and amorphous-oxide forms (CoO• Co 2 O 3) and of phosphorus as phosphide and orthophosphate. The orthophosphate species, produced by air-oxidation, were eliminated upon HER electrocatalysis in sulfuric acid. The operando film purification yielded a functional electrocatalyst with a Co:P stoichiometric ratio of 1:1. After the HER, the surface was densely packed with micrometer-sized, mesa-like particles whose tops were flat and smooth. The CoP eletrodeposit exhibited an 85 mV overvoltage (η) for the HER at a current density of 10 mA cm −2 and was stable under operation in highly acidic solution, with an increase in η of 18 mV after 24 h of continuous operation. The comparative HER catalytic performance of CoP, film or nanoparticles, is as follows: η Pt < η CoP film = η CoP NP , η Ni 2 P < η CoSe 2 < η MoS 2 < η MoSe 2 .
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