Christopher P. Muzzillo

Christopher P. Muzzillo
National Renewable Energy Laboratory | NREL · National Center for Photovoltaics

Doctor of Philosophy

About

75
Publications
9,455
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996
Citations

Publications

Publications (75)
Article
Full-text available
We demonstrate the new concept of using unit cell volume coefficient of variation to approximate the enthalpic penalty of high-entropy alloy (HEA) candidates, and use it along with configurational entropy to map promising HEA halide perovskites.
Article
A hierarchical transparent back contact leveraging an AlGaOx passivating layer, Ti3C2Tx MXene with a high work function, and a transparent cracked film lithography (CFL) templated nanogrid is demonstrated on copper-free cadmium telluride (CdTe) devices. AlGaOx improves device open-circuit voltage but reduces the fill factor when using a CFL-templat...
Article
Full-text available
Despite the outstanding progress in performance of halide perovskite solar cell absorbers fab-ricated via vapor-based approaches, increasing deposition rates as well as enabling continuous deposition has been woefully neglected. In...
Article
Full-text available
Nitride perovskites are an emerging class of materials that have been predicted to display a range of interesting physics and functional properties, but they are highly underexplored due to the difficulty of synthesizing oxygen-free nitrides. LaWN3, recently reported as the first oxygen-free nitride perovskite, exhibited polar symmetry and a large...
Preprint
Full-text available
Nitride perovskites are an emerging class of materials that have been predicted to display a range of interesting physics and functional properties, but they are under-explored due to the difficulty of synthesizing oxygen-free nitrides. LaWN3, recently reported as the first oxygen-free nitride perovskite, exhibited polar symmetry and a large piezoe...
Article
Full-text available
Bifacial CdTe solar cells with greater power density than the monofacial baselines are demonstrated by using a CuGaOx rear interface buffer that passivates while reducing sheet resistance and contact resistance. Inserting CuGaOx between the CdTe and Au increases mean power density from 18.0 ± 0.5 to 19.8 ± 0.4 mW cm⁻² for one sun front illumination...
Article
We report on a semi-monolithic integration method to circumvent processing incompatibility between materials of dissimilar classes and combine them into multijunction devices for photovoltaic and photoelectrochemical applications. Proof-of-concept all-chalcopyrite tandems were obtained by consecutive transfer of fully integrated unpatterned 1.85 eV...
Article
RbF post-deposition treatments have been explored in the literature for increasing the open-circuit voltage, fill factor, and hence the efficiency of Cu(In,Ga)Se2 solar cells. However, given the few papers documenting the experimental steps, it was difficult to quickly reproduce the results. This contribution describes some of the optimization step...
Article
Full-text available
Anand et al. introduce an implicit equation for transparent conductive electrode (TCE) merit in photovoltaics (PV) by lumping series resistance in with the diode. However, an explicit equation has been previously derived by lumping series resistance external to the diode. For TCEs of practical interest for PV, the choice of where to lump series res...
Article
In this work we test field-relevant potential-induced degradation (PID) behavior by encapsulating laboratory Cu(In,Ga)Se2 (CIGS) solar cells and applying +1000 V uniformly on the face of the front glass. In this configuration, we find that K-rich borosilicate glass reduces the extent of PID relative to Na-rich soda-lime glass. We also find that the...
Article
Full-text available
Correction for ‘Performance and limits of 2.0 eV bandgap CuInGaS 2 solar absorber integrated with CdS buffer on F:SnO 2 substrate for multijunction photovoltaic and photoelectrochemical water splitting devices’ by Nicolas Gaillard et al. , Mater. Adv. , 2021, DOI: 10.1039/D1MA00570G.
Article
Full-text available
We report on the electrical properties of 2.0 eV bandgap (EG) CuInGaS2 (CIGS) solar absorbers integrated on SnO2:F (FTO) substrates and interfaced with CdS buffer layers for multijunction solar cells and photoelectrochemical water splitting devices. The averaged short-circuit photocurrent density measured on nine ITO/ZnO/CdS/CIGS/FTO cells was 10.0...
Article
We report an efficiency enhancement of solution-processed CuIn(S,Se)2(CISSe) thin film solar cellsvia in situincorporation of Al2O3. These films were produced using inks containing CuCl, InCl3, AlNO3(Al/Al + In: 0.1) and thiourea dissolved in methanol. After spin coating of these solutions in air, samples were subjected to a selenization process. A...
Article
Polycrystalline photovoltaic materials offer low costs and good scalability; however, grain boundaries in these materials are extended defects, which can drastically increase carrier recombination. Interestingly, three leading polycrystalline thin-film technologies—cadmium telluride (CdTe), CuIn1-xGaxSe2 (CIGS), and perovskite solar cells (PSCs)—pa...
Article
Full-text available
CuGa3Se5 is a promising candidate material with wide band gap for top cells in tandem photovoltaic (PV) and photoelectrochemical (PEC) devices. However, traditional CdS contact layers used with other chalcopyrite absorbers are not suitable for CuGa3Se5 due to the higher position of its conduction band minimum. MgxZn1-xO is a transparent oxide with...
Article
This work demonstrates that ultrathin (4 nm) tungsten oxide (WO3) coatings on copper gallium selenide (CuGa3Se5) photocathodes have the potential for long-term solar hydrogen evolution. With a combination of a robust 1.84 eV CuGa3Se5 absorber layer, a WO3 protective coating, and a Pt catalyst, we obtain a new durability milestone for any non-silico...
Preprint
Full-text available
CuGa_3Se_5$ is a promising candidate material with wide band gap for top cells in tandem photovoltaic (PV) and photoelectrochemical (PEC) devices. However, traditional CdS contact layers used with other chalcopyrite absorbers are not suitable for $CuGa_3Se_5$ due to the higher position of its conduction band minimum. $Mg_xZn_{1-x}O$ is a transparen...
Article
We introduce cracked film lithography (CFL) as a way to reduce the cost of III-V photovoltaics (PV). We spin-coat nanoparticle suspensions onto GaAs thin-film device stacks. The suspensions dry in seconds, forming crack networks that we use as templates through which to electroplate the solar cells’ front metal grids. For the first time, we show th...
Article
Cracked film lithography (CFL) is an emerging method for patterning transparent conductive metal grids. CFL can be vacuum- and Ag-free, and it forms more durable grids than nanowire approaches. In spite of CFL’s promising transmittance/grid sheet resistance/wire spacing tradeoffs, previous solar cell demonstrations have had relatively low performan...
Article
The fundamentals of using cracked film lithography (CFL) to fabricate metal grids for transparent contacts in solar cells were studied. The underlying physics of drying-induced cracks were well-predicted by an empirical correlation relating crack spacing to capillary pressure. CFL is primarily controlled by varying the crack template thickness, whi...
Article
Workers in the field of solar water splitting have had success in synthesizing devices that approach the 20% solar-to-hydrogen efficiency metric required for economically feasible hydrogen production. However, these devices rely upon expensive epitaxial synthetic techniques and have not yet achieved technologically-meaningful durability metrics. Th...
Article
Potential-induced degradation (PID) of encapsulated Cu(In,Ga)Se $_2$ (CIGS) solar cells was studied for different substrates: soda-lime glass (SLG), SLG with an Al $_2$ O $_3$ diffusion barrier, and borosilicate glass (BSG). The Al $_2$ O $_3$ and BSG samples increased the time to PID failure by 5x and 30x, respectively. The relationship betwe...
Article
This work shows a bimolecular additive engineering approach to prepare highly efficient wide-band-gap perovskite solar cells. The coupling of PEA + and SCN À provides a synergistic effect that overcomes growth challenges with either additive individually and improves perovskite quality with enhanced crystallinity, reduced defect density, and improv...
Article
Potential-induced degradation (PID) is investigated in small-size Cu(In,Ga)Se $_{2}$ (CIGS) submodules of individual cells. Samples with conventional soda-lime glass (SLG) and low-alkaline glass (borosilicate glass, BSG) were analyzed applying positive and negative 1000 V bias at 85 °C and low relative humidity after a heat-soaking phase. During t...
Article
The cover image, by Christopher P. Muzzillo et al., is based on the Research Article Revealing the beneficial role of K in grain interiors, grain boundaries, and at the buffer interface for highly efficient CuInSe2 solar cells, https://doi.org/10.1002/pip.3022.
Article
Potential-induced degradation (PID) of photovoltaic modules is due to transport of alkali metal ions (Na+) from the soda-lime glass (SLG) into the semiconductors. For the most efficient polycrystalline absorbers, Na and K in the Cu(In,Ga)(Se,S) $_{2}$ (CIGS) absorber often benefit performance, so a more detailed mechanism for PID is needed. To tha...
Article
K incorporation within grain boundaries, grain interiors, and interfaces has been studied within CuInSe2 solar cells to better understand the beneficial or detrimental role of K distribution among these regions in chalcopyrite‐based solar cells. Solar cells have been fabricated with intentional K introduction into specific regions of the device inc...
Article
Two strategies for enhancing photovoltaic (PV) performance in chalcopyrite solar cells were investigated: Cu1−xKxIn1−yGaySe2 absorbers with low K content (K/(K+Cu), or x ~ 0.07) distributed throughout the bulk, and CuIn1−yGaySe2 absorbers with KIn1−yGaySe2 grown on their surfaces. Distributing K throughout the bulk absorbers improved power conversi...
Article
Photoelectrochemical (PEC) water-splitting is an elegant method of converting sunlight and water into H2 fuel. To be commercially advantageous, PEC devices must become cheaper, more efficient and much more durable. This work examines low-cost polycrystalline chalcopyrite films, which are successful as photovoltaic absorbers, for application as PEC...
Article
Full-text available
The Ag–Cu–In thermodynamic material system is of interest for brazing alloys and chalcopyrite thin-film photovoltaics. To advance these applications, Ag–Cu–In was assessed and a Calphad model was developed. Binary Ag–Cu and Cu–In parameters were taken from previous assessments, while Ag–In was re-assessed. Structure-based models were employed for β...
Article
Co-evaporation of Cu-KF-In-Se was performed on substrates with varied Na supply. Compositions of interest for photovoltaic absorbers were studied, with ratios of (K + Cu)/In ∼ 0.85 and K/(K + Cu) ∼ 0–0.57. Bare soda-lime glass (SLG) substrates had the highest Na supply as measured by secondary ion mass spectrometry, while SLG/Mo and SLG/SiO2/Mo sub...
Data
This is the thermodynamic database file (.tdb file) for the Ag-Cu-Ga-In material system to be used with Pandat 2016. Use with Thermo-Calc may require debugging.
Data
This is the thermodynamic database file (.tdb file) for the Ag-Cu-Ga-In material system to be used with Pandat 2016. Use with Thermo-Calc may require debugging.
Article
Introducing K into Cu(In,Ga)(Se,S)2 (CIGS) absorbers has led to recent world record power conversion efficiencies for thin film polycrystalline solar cells. In this work, the diverse phenomena associated with K in CIGS were reviewed, and overarching mechanisms were identified. The effects of K depend on its distribution among grain interiors (GIs),...
Article
A general procedure for predicting metal grid performance in solar cells was developed. Unlike transparent conducting oxides (TCOs) or other homogeneous films, metal grids induce more resistance in the neighbor layer. The resulting balance of transmittance, neighbor and grid resistance was explored in light of cheap lithography advances that have e...
Article
To advance knowledge of K bonding in Cu(In,Ga)(Se,S)2 (CIGS) photovoltaic (PV) absorbers, recent Cu-K-In-Se phase growth studies have been extended to PV performance. First, the effect of distributing K throughout bulk Cu1-xKxInSe2 absorbers at low K/(K+Cu) compositions (0 <= x <= 0.30) was studied. Efficiency, open-circuit voltage (VOC), and fill...
Article
Two strategies for enhancing photovoltaic (PV) performance in chalcopyrite solar cells were investigated: Cu1-xKxIn1-yGaySe2 absorbers with low K content (K/(K+Cu), or x ~ 0.07) distributed throughout the bulk, and CuIn1-yGaySe2 absorbers with KIn1-yGaySe2 grown on their surfaces. For the Ga-free case, increased temperature improved PV performance...
Article
The deliberate introduction of K and Na into Cu(In, Ga)Se <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (CIGS) absorbers was investigated by varying a combination of an SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> diffusion barrier...
Article
To advance knowledge of K bonding in Cu(In,Ga)(Se,S)2 (CIGS) photovoltaic (PV) absorbers, recent Cu-KIn -Se phase growth studies have been extended to PV performance. First, the effect of distributing K throughout bulk Cu1-xKxInSe2 absorbers at low K/(K+Cu) compositions (0 ≤ x ≤ 0.30) was studied. Efficiency, open-circuit voltage (VOC), and fill fa...
Article
Full-text available
Adding potassium to Cu(In,Ga)Se2 absorbers has been shown to enhance photovoltaic power conversion efficiency. To illuminate possible mechanisms for this enhancement and limits to beneficial K incorporation, the properties of Cu1−x Kx InSe2 (CKIS) thin-film alloys have been studied. Films with K/(K + Cu), or x, from 0 to 1 were grown by co-evaporat...
Article
Films of Cu-KIn -Se were co-evaporated at varied K/(K+Cu) compositions and substrate temperatures (with constant (K+Cu)/In ~ 0.85). Increased Na composition on the substrate's surface and decreased growth temperature were both found to favor Cu1-xKxInSe2 (CKIS) alloy formation, relative to mixed-phase CuInSe2 + KInSe2 formation. Structures from X-r...
Conference Paper
Thin CuGa/In films with varied compositions were deposited by co-evaporation and then selenized in situ with evaporated selenium. The selenized Cu(In,Ga)Se2 absorbers were used to fabricate 390 solar cells. Cu/(Ga+In) and Ga/(Ga+In) (Cu/III and Ga/III) were independently varied, and photovoltaic performance was optimal at Cu/III of 77 – 92% for all...
Article
Full-text available
Both experimental measurements and assessment of phase equilibria are reported in the Cu–Ga–In material system, which is an important constituent in growth of the thin film photovoltaic absorber Cu(In,Ga)Se2 (CIGS). Characterization of four different alloys using inductively coupled plasma atomic emission spectroscopy, X-ray diffraction, scanning e...
Thesis
Full-text available
Aspects of chalcopyrites have been researched for their use as absorbers in solar cells. Atmospheric pressure chloride chemical vapor deposition (CVD) of Cu(In,Ga)Se2 was examined by complex chemical equilibria calculations. The transport of Cu, Ga, and In by HCl gas reaction was characterized for CVD, in addition to evaporative CuCl and Se transpo...
Article
Full-text available
Fiber-fed time-resolved photoluminescence is demonstrated as a tool for immediate process feedback after deposition of the absorber layer for CuInxGa1-xSe2 and Cu2ZnSnSe4 photovoltaic devices. The technique uses a simplified configuration compared to typical laboratory time-resolved photoluminescence in the delivery of the exciting beam, signal col...
Conference Paper
Full-text available
Reaction pathways were followed for selenization of CuGa/In precursor structures using in-situ high temperature X-ray diffraction (HTXRD). Precursor films were deposited on Na-free and Na-doped Mo (3 and 5 at %)/Na-free glass. The precursor film was constituted with CuIn, In, Cu9Ga4, Cu3Ga, Cu16In9 and Mo. HTXRD measurements during temperature ramp...
Article
Previously, the synthesis of highly oriented pure double-gyroid nanoporous silica films has been demonstrated using evaporation-induced self-assembly (EISA) and dip-coating with a specialty triblock surfactant (PEO-PPO-alkyl) as the template. For these films, grazing-incidence small-angle X-ray scattering (GISAXS) was used to determine orientation...
Article
Ordered mesoporous silica thin films were prepared using non-ionic alkyl poly(oxyethylene) surfactants (Brij56: C18EO10) by a vapor phase method. First, a Brij56/H2SO4 composite was deposited on a silicon substrate by spin-coating. The Brij56 film was treated with a tetraethoxysilane (TEOS) and hydrochloric acid (HCl) vapors in a closed vessel. The...

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