Engineering topics

Tuller, Harry

Publications and source records attributed to Tuller, Harry.

4 records

DOE OSTI2023

Influence of Codeposition on Methylammonium Iodide Degradation during Vapor Transport Deposition

Vapor transport deposition (VTD) is one manufacturing-compatible technique for large-scale deposition of perovskite films. However, to date, little understanding has been given to degradation products formed by perovskites grown under vacuum. Here, we use methylammonium iodide (MAI) as an example organic precursor to identify degradation patterns through both the sublimation process and transport through a zone with temperatures much higher than MAI can thermodynamically survive. We show that degradation due to sublimation effects MAI powders and subsequent integration into methylammonium lead iodide (MAPbI3) films differently than degradation solely due to material transport through a very high-temperature zone. Additionally, we categorize common post-deposition treatments by their influence on the degradation products seen in MAPbI3 films. Furthermore, with these results we give recommendations for VTD reactor design and the feasibility of co-deposition as a film growth technique.

14 SOLAR ENERGY↗

DOE OSTI2023

Surface electron modulation of metal oxide‐based electrochemical devices by surface additives—linking sensors and fuel cells

Abstract The interaction between ambient oxygen and the metal oxide surface is central to various electrochemical devices. Solid oxide fuel cell cathodes and semiconducting metal oxide gas sensors are two prominent examples. Parallels between these two systems are highlighted in this perspective. In both cases, the presence of foreign surface species has been found to significantly alter the interactions of the metal oxides’ surfaces with oxygen. On the one hand, interactions are hindered due to the presence of certain impurities, such as the degradation of fuel cell cathode by Si‐species that originate from processing or from operating environments. On the other hand, electrochemically active noble metal additives have been intentionally used to tune the sensor response of metal oxides. In the case of electrochemically active additives, the need for operando spectroscopies to elucidate the mechanism is discussed. Electronic coupling of the surface additive with the metal oxide is found to play a central role in both cases. We use these results to demonstrate that insights gained from either field can be effectively applied to the other.

Materials Science↗

DOE OSTI2023

Design of a custom vapor transport co-deposition system for scalable production of perovskite solar cells

Vacuum-deposited perovskites provide a more direct path to manufacturing large area solar cells because of ready compatibility with multilayered architectures and historic use in the electronics industry. However, vacuum compatible co-deposition of organic-inorganic perovskites remains difficult due to issues of precisely controlling the organic precursor flux. Here, we demonstrate a manufacturing prototype specifically designed for co-depositing organic-inorganic perovskites and evaluate it with respect to the influence of process parameters on film growth. Through depositing and characterizing methylammonium lead iodide (MAPbI3) perovskite films, we highlight the necessary design requirements while measuring the influence of film growth parameters on deposition rate and perovskite phases.

14 SOLAR ENERGY↗

DOE OSTI2019

Self-regulating surface chemistry for more robust highly durable solid oxide fuel cell cathodes

In this project we explored the possibility of mitigating silicon poisoning of Pr doped ceria (PCO) electrodes for oxygen reduction in SOFC. The approach was to dope PCO with various amount of lanthanum and study the new compositions in terms of their mixed conduction properties, their oxygen surface exchange kinetics, as well as their resistance to silicon poisoning. The effects of lanthanum doping on the transport properties and oxygen exchange kinetics of La x (Ce 0.9 Pr 0.1 ) 1-x O 2-δ (x=0, 0.1 and 0.2) have been investigated by electrical conductivity on bulk samples and optical relaxation on thin films respectively. Lanthanum substitution was observed to increase the magnitude of ionic conductivity to values comparable to that of single substituted La x Ce 1-x O 2-δ , with a maximum for a La content of x = 0.1, reaching σ = 9.5×10 -3 S·cm -1 at 600 °C and a decrease in activation energy from ≈ 1 eV for Ce 0.9 Pr 0.1 O 2-δ down to ≈ 0.75 eV for the lanthanum substituted compositions. At the same time, a significant electronic contribution to the total conductivity, estimated to be on the order of 10%, supports significant mixed ionic-electronic conductivity.

08 HYDROGEN↗