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DOE OSTI2021

Life cycle energy demand and carbon emissions of scalable single-junction and tandem perovskite PV

Perovskite photovoltaics reached record efficiencies in the laboratory and, if sustainably commercialized, they would accelerate a green energy transition. Here, this article presents the development of life-cycle inventory material and energy databases of most promising four single-junction and three tandem scalable perovskite systems with assumptions regarding scalable production validated by industry experts. We conducted comprehensive “ex ante” Life Cycle Analysis (LCA) and Net Energy Analysis, analyzing their cumulative energy demand, global warming potential profiles, energy payback times and energy return on investment (EROI). LCA contribution analysis elucidates the most impactful material and process choices. It shows that solution-based perovskite manufacturing would have lower environmental impact than vapor-based methods, and that roll-to-roll (RtR) printing offers the lowest impact. Among material choices, MoOx/Al has lower impact than Ag, and fluorine-tin-oxide lower than indium-tin-oxide. Furthermore, we compare perovskites with commercial crystalline-silicon and thin-film PV, accounting for the most recent developments in crystalline-Si wafer production and differences in life expectancies and efficiencies. It is shown that perovskite systems produced with RtR manufacturing could reach in only 12 years of life the same EROI as that of single-crystalline-Si PV lasting 30-years. This work lays a foundation for sustainability investigations of perovskite large-scale deployment.

14 SOLAR ENERGY↗

DOE OSTI2020

Electrical injection and transport in Teflon-diluted hole transport materials

Diluting small molecule organic semiconductor hole transport materials with Teflon AF (TAF) dramatically increases their thermal/morphological stability while counterintuitively also increasing the current density in hole-only diodes. Here, we explore the origin of this current enhancement in co-evaporated blends of TAF and N,N'-Di(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPD) and find that it results from improved hole injection and not from a mobility enhancement due to semiconductor dilution effects. Whereas electroabsorption measurements indicate that an interface dipole shift of up to 0.5 eV (depending on TAF concentration) aides hole injection at the indium-tin-oxide anode, time-of-flight and temperature-dependent current-voltage measurements show that the mobility of 25 vol% TAF:NPD blends decreases by roughly an order of magnitude relative to neat NPD despite having slightly lower energetic disorder. For comparison, diluting with 25 vol% high density polyethylene achieves a similar reduction in energetic disorder but only decreases the mobility by a factor of two. Furthermore, these results highlight the tradeoff between reducing energetic disorder and frustrating percolation in diluted organic semiconductors, and represent a step toward thermally-evaporated polymer-small molecule composites that maintain high mobility while offering improved morphological stability and lower refractive index for organic light emitting diodes.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2024

Durability enhancement of all-solid-state electrochromic devices by adjusting the charge density ratio between electrochromic and counter electrode layers

Here, owing to an increase in global warming, smart-window devices based on charge-balanced electrochromic devices (ECDs), which exhibit high potential to increase the thermal efficiency of buildings, have gained prominence. However, studies on the fabrication and cycling stability of charge-balanced ECDs are scarce. In this study, WO 3 and NiO x films were deposited on indium-tin-oxide (ITO)-coated glass substrates by reactive direct-current magnetron sputtering, and the deposition time was varied to control the thickness and charge density of the thin films. Subsequently, the NiO x /ITO/glass and WO 3 /ITO/glass substrates were laminated with a Li-based polymeric electrolyte to fabricate all-solid-state ECDs comprising electrochromic (EC) and counter-electrode (CE) layers in charge-density ratios of 12.6, 6.4, 2.3, and 1.1. Changes in the electrochromic properties, device-layer microstructure, crystal structure, and elemental composition of the as-constructed ECDs before and after degradation were investigated to understand the influence of the charge-density ratio of the EC and CE layers on the long-term durability of ECDs. Increasing the charge-density ratio decreased the cycling stability of the device owing to changes in the microstructure and crystal structure of the NiO x layer in the microstructural deep-trap sites. Among all the ECDs, those comprising EC and CE layers with similar charge densities showed the most stable optical modulation and highest long-term durability. Finally, based on the aforementioned results, a degradation mechanism for charge-imbalanced all-solid-state ECDs was proposed. This study is expected to open new frontiers in designing optimal-performance electrochemical devices with a wide variety of potential applications.

14 SOLAR ENERGY↗

DOE OSTI2021

Out of the Lab: 3D Printing on Non-Ideal Surfaces

In this work, coaxial direct ink writing is utilized to print sensitive or encapsulated materials onto heterogeneous and rough substrates. By enclosing the core fluid within a rigid ceramic shell, continuity is maintained even when printing on substrates traditionally considered challenging. This work presents the development of a coaxial ceramic direct ink writing system and investigates co-flow dynamics through microfluidic principles. A specially designed coaxial nozzle enables the co-extrusion of an alumina shell, with indium-tin-oxide inks serving as the core material. This approach allows the fabrication of core-shell ceramic structures suitable for future high-temperature applications on rough surfaces. The colloidal inks are tailored to achieve the necessary rheological properties and sintering performance. Additionally, flow simulations, guided by microfluidic co-flow principles, are employed to define the processing parameters for coaxial printing, ensuring precise control over the core-shell architectures. Physical modeling is further applied to study core deformation and eccentricity. These simulations are experimentally validated, supporting the successful deposition of coaxial ceramic features on heterogeneous, high-temperature ceramic substrates.

20 FOSSIL-FUELED POWER PLANTS↗

DOE OSTI2020

Organic-semiconducting hybrid solar cell

The embodiment of this invention lies on experimental evidence of photoconductivity activity of a hybrid solar cell, organic/chalcogenide. The device is made of thin layers of conductive indium-tin-oxide (ITO) on glass with a 100 nm layer of chalcogenide molybdenum di-sulfide (MoS 2 ) and a thin layer of about ˜50 nm of complex organic compound assembled at room temperature. The device was tested to conventional electrical transport measurements in the regime of −1V to 1V under electromagnetic radiation simulator at 100 mW/cm 2 . Results indicate solar conversion efficiency of 2.48% and current density of 6.35 mA/cm 2 .

14 SOLAR ENERGY↗

DOE OSTI2021

Potential dependent spectroelectrochemistry of electrofluorogenic dyes on indium–tin oxide

Indium-tin oxide (ITO) is used in a variety of applications due to its electrical conductivity and optical transparency. Moreover, ITO-coated glass is a common working electrode for spectroelectrochemistry. Thus, the ITO substrates should exhibit well-understood spectroscopic characteristics. Here, we report anomalous potential-dependent luminescence emission from three structurally dissimilar electrofluorogenic probe on ITO-coated glass. The three probes, flavin mononucleotide, resorufin, and Nile blue, show the expected fluorescence modulation between their oxidized, emissive forms and their reduced, nonfluorescent forms at low laser irradiance and/or high concentrations. However, at high irradiance and/or low concentration, the emission intensity increases at reducing potentials, contrary to expectations. In addition, a strong interplay between probe molecule concentration and laser irradiance is observed. We attribute the anomalous behavior to a combination of (1) irradiance-dependent ITO carrier dynamics, and (2) interaction of the fluorescent probe with ITO at reducing potentials resulting in a charge transfer state with altered emission behavior. Thus, the potential- and irradiance-dependent behavior of ITO and the resulting charge transfer state may not only interfere with the observation of potential-dependent fluorescence from redox probes but can completely reverse the polarity of the potential-dependent luminescence, especially at high irradiance and low concentration.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗