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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,531 records · Page 85
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

C60-Based Ionic Salt Electron Shuttle for High-Performance Inverted Perovskite Solar Modules

Although C60 is usually the electron transport layer (ETL) in inverted perovskite solar cells, its molecular nature of C60 leads to weak interfaces that lead to non-ideal interfacial electronic and mechanical degradation. Here, we synthesized an ionic salt from C60, 4-(1',5'-dihydro-1'-methyl-2'H-[5,6] fullereno-C60-Ih-[1,9-c]pyrrol-2'-yl) phenylmethanaminium chloride (CPMAC), and used it as the electron shuttle in inverted PSCs. The CH2-NH3+ head group in the CPMA cation improved the ETL interface and the ionic nature enhanced the packing, leading to ~3-fold increase in the interfacial toughness compared to C60. Using CPMAC, we obtained ~26% power conversion efficiencies (PCEs) with ~2% degradation after 2,100 hours of 1-sun operation at 65degrees C. For minimodules (four subcells, 6 centimeters square), we achieved the PCE of ~23% with <9% degradation after 2,200 hours of operation at 55degrees C.

14 SOLAR ENERGY↗
DOE OSTI2025

Chirality-Induced Spin Selectivity in Hybrid Organic-Inorganic Perovskite Semiconductors

The movement of charges through a chiral medium results in a spin-polarized charge current. This phenomenon, known as the chirality-induced spin selectivity (CISS) effect, enables control over spin populations without the need for magnetic components and operates at room temperature. CISS has been discovered in a range of chiral media and most prominently studied in chiral organic molecular species. Chiral hybrid organic-inorganic perovskite semiconductors combine the unique and functional aspects of inorganic semiconductors with chiral molecules. The inorganic component borrows the homochirality of the organic component to yield a unique family of highly tunable chiral semiconductors, where the enantiomeric purity is defined by the organic component. Semiconductors already form the backbone of modern-day technologies. Adding chirality and control over spin through CISS provides new avenues for creative technological development. This review is intended to be an introduction to these unique systems and the demonstrations of CISS and spin control.

14 SOLAR ENERGY↗
DOE OSTI2023

Optical anisotropy of CsPbBr3 perovskite nanoplatelets

Abstract The two-dimensional CsPbBr 3 nanoplatelets have a quantum well electronic structure with a band gap tunable with sample thicknesses in discreet steps based upon the number of monolayers. The polarized optical properties of CsPbBr 3 nanoplatelets are studied using fluorescence anisotropy and polarized transient absorption spectroscopies. Polarized spectroscopy shows that they have absorption and emission transitions which are strongly plane-polarized. In particular, photoluminescence excitation and transient absorption measurements reveal a band-edge polarization approaching 0.1, the limit of isotropic two-dimensional ensembles. The degree of anisotropy is found to depend on the thickness of the nanoplatelets: multiple measurements show a progressive decrease in optical anisotropy from 2 to 5 monolayer thick nanoplatelets. In turn, larger cuboidal CsPbBr 3 nanocrystals, are found to have consistently positive anisotropy which may be attributed to symmetry breaking from ideal perovskite cubes. Optical measurements of anisotropy are described with respect to the theoretical framework developed to describe exciton fine structure in these materials. The observed planar absorption and emission are close to predicted values at thinner nanoplatelet sizes and follow the predicted trend in anisotropy with thickness, but with larger anisotropy than theoretical predictions. Dominant planar emission, albeit confined to the thinnest nanoplatelets, is a valuable attribute for enhanced efficiency of light-emitting devices.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2020

The underappreciated lone pair in halide perovskites underpins their unusual properties

The presence of 6s 2 (5s 2 ) lone-pair electrons on the B-site Pb (Sn) in all-inorganic and hybrid halide ABX 3 perovskites distinguishes these materials from the familiar tetrahedral semiconductors traditionally employed in optoelectronics and is key to many of their appealing properties. These electrons are stereochemically active, albeit often in a hidden fashion, resulting in unusual and highly anharmonic lattice dynamics that are linked to many of the special optoelectronic properties displayed by this material class. This article describes the connections between this atypical electronic configuration and the electronic structure and lattice dynamics of these compounds. We illustrate how the lone pair leads to favorable bandwidths and band alignments, mobile holes, large ionic dielectric response, large positive thermal expansion, and even possibly defect-tolerant electronic transport. Taken together, the evidence suggests that other high-performing semiconductors may be found among compounds with lone-pair-bearing cations in high symmetry environments and a high degree of connectivity between atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Blinking compromises the single-photon purity of individual CsPbBr 3 perovskite nanocrystals

Individual lead halide perovskite nanocrystals (PNCs) are promising single photon emitters but often suffer from photoluminescence blinking. Here, we correlate the photoluminescence blinking behavior of CsPbBr 3 NCs with their second-order correlation functions. We find that even moderate band-edge carrier blinking (BC-blinking) can significantly decrease the PNC’s single photon purity, while the impact from Auger blinking is much smaller. Additionally, the degree of BC-blinking can introduce significant uncertainties in single photon purity compared to PNCs with suppressed blinking. Furthermore, we quantitatively correlate the decrease in single photon purity with BC-blinking severity.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Inkjet Printing to Scale Perovskite and Silicon Tandem Solar Cell: Cooperative Research and Development Final Report, CRADA Number CRD-17-00690

The proposed project seeks to develop a method for inkjet printing of the active layer in perovskite solar cells for application in stand-alone products or added to conventional silicon solar cells in a mechanically-stacked tandem configuration. This technology presents significant advanced manufacturing challenges and opportunities in getting to scale, including development of novel uses for printing technologies and development of predictive quality control techniques.

14 SOLAR ENERGY↗
DOE OSTI2021

Multi-Messenger In-situ Tolerance Optimization of Mixed Perovskite Photovoltaics. Final Report

The main objectives for this project were to formulate, validate and disseminate a new procedure based on Environmental X-ray Photoelectron Spectroscopy (EXPS) for the accelerated degradation testing of metal hybrid perovskite (MHP) PV materials. With this capability, we can aid US efforts to improve MHP tolerance for illumination in damp heat conditions. This capability will benefit the public by supporting new industry efforts to create stable MHP formulations.

14 SOLAR ENERGY↗
DOE OSTI2024

Surface Ligand Effects on Energetics, Charge Transfer, and Stability at Interfaces Between Metal Halide Perovskites and Organic Semiconductors

Chemistry at organic-inorganic interfaces plays a major role in determining the performance of electronic and optoelectronic devices. Understanding, developing, and using surface chemistry is thus essential for creating improved and novel materials and devices. Organic metal halide perovskites (HPs) are inexpensive semiconductors that can be printed from solution to make efficient photovoltaic cells for harvesting solar energy, light emitting diodes for energy efficient solid-state lighting applications, solid-state lasers, and even spin selective devices with applications to quantum computing. To realize the potential of HPs, their surface chemistry and interfacial properties must be better understood and appropriately adjusted to meet the needs of the targeted application. For example, surface chemistry influences non-radiative recombination, which influences the efficiency of light emission and solar energy conversion, charge-carrier injection and extraction from optoelectronic devices, and material and device stability. This research project centered around determining how the surface chemistry of HP thin films and nanoparticles influences optical properties, charge transfer processes, energetics, and stability. In this project we characterized ligand binding strengths to HPs; determined how surface ligand chemistry influences photoluminescence properties, energetics, and charge transfer processes; determined that surface ligands often penetrate into HPs and uncovered methods of reducing surface ligand penetration through structural modifications; and discovered how interfacial energetics impact charge transfer processes and photovoltaic performance parameters. Overall, this research established important insights into how surface ligands interact with HPs to influence their optical properties, electronic properties, stability, and device level performance.

14 SOLAR ENERGY↗
DOE OSTI2024

Triple_Conducting_Perovskite_Defect_Model

An Octave based script for solving defect thermodynamic model to generate Brouwer diagram of triple conducting perovskite as a function of temperature, P(O2)/P(H2O), or P(H2)/P(H2O) based on nonstoichiometry dependent defect formation energies and entropies.

Brouwer diagram↗
DOE OSTI2024

Remanufacturable "Net-Zero Pb" Perovskite Solar Modules

Our introduced a low-cost recycling method for perovskite PV cells which utilize KI salt-based solvents, a more sustainable chemical compared to commonly used chemicals such as DMF, chlorobenzene etc. All steps of the recycling method were demonstrated in detail in publications and presentations of the team. In addition, the techno-economic team demonstrated that the KI-based method is a more promising option compared to other methods investigated in the literature.

14 SOLAR ENERGY↗
DOE OSTI2025

Scribe and Interface Modification for Stable Halide Perovskite Modules (CRADA Final Report)

This project provided funding to NREL/Tandem PV by EERE-SETO and has the goal of improving perovskite module stability by at least a factor of 2 without sacrificing initial efficiency. This will be demonstrated using 3"x3" minimodules and will be tested according to the Innovation and Entrepreneurship Center (IEC) standards and demonstrated using outdoor testing. A CRADA was established between NREL and Tandem PV to address the goals for the funded effort.

14 SOLAR ENERGY↗
DOE OSTI2025

First-Principles Thermodynamic Assessments of Sr-Containing Secondary Phase Formation in La1-xSrxMnO3±δ Perovskites for Solid Oxide Cell Applications

Sr-secondary phase formation is a potentially significant degradation mode threatening solid-oxide cell (SOC) commercial viability. A first-principles thermodynamic study was performed for rhombohedral perovskite (La1-xSrx) MnO3±δ (LSM) to assess its stability against Sr secondary phase formation in SOC applications. In this work, the Sr secondary phase formation reaction free energies were determined by combining ab initio lattice dynamics calculations for the solid phases and an ab initio thermodynamics approach for the gas phases. Furthermore, this approach goes beyond previous thermodynamic modeling studies by integrating first-principles based point-defect equilibria into the analyses. The modeling results indicate an increased tendency to form SrO oxide from LSM upon decreasing the oxygen partial pressure. Additionally, enhancing factors to form the Sr-related secondary phase from the associated SrO activity in LSM are further quantified by considering the equilibrium of SrO reacting with contaminant gas species as a function of temperature and gas pressure.

Defect and phase stability↗