A series of perylene diimide cathode interlayer materials for green solvent processing in conventional organic photovoltaics.

Herein, we report on the design, synthesis, physical and chemical properties, and organic photovoltaic (OPV) device performance of four new cathode interlayer (CIL) materials based on bay N-annulated perylene diimides. Starting from the previously reported N-annulated perylene diimide (PDIN-H), the N-position was functionalized with a benzyl and pentafluorobenzyl group to make PDIN-B and PDIN-FB, respectively. Similarly, starting from the previously reported cyanated N-annulated perylene diimide (CN-PDIN-H), the N-position was functionalized with a benzyl and pentafluorobenzyl group to make CN-PDIN-B and CN-PDIN-FB, respectively. The materials exhibit solubility in the green solvent, ethyl acetate, and thus were processed into thin films using ethyl acetate as the solvent. The optoelectronic properties were assessed for both solution and film, and the electrochemical properties were probed in solution. To validate the potential as electron transporting layers, each film was used in conventional OPVs as the CIL with processing from ethyl acetate, while using a bulk heterojunction (BHJ) comprised of PM6:Y6. High power conversion efficiencies (PCEs) of 13% were achieved compared to control devices using the standard PFN-Br CIL.

Visual Facial Enhancements Can Significantly Improve Speech Perception in the Presence of Noise.

Human speech perception is generally optimal in quiet environments, however it becomes more difficult and error prone in the presence of noise, such as other humans speaking nearby or ambient noise. In such situations, human speech perception is improved by speech reading, i.e., watching the movements of a speaker's mouth and face, either consciously as done by people with hearing loss or subconsciously by other humans. While previous work focused largely on speech perception of two-dimensional videos of faces, there is a gap in the research field focusing on facial features as seen in head-mounted displays, including the impacts of display resolution, and the effectiveness of visually enhancing a virtual human face on speech perception in the presence of noise. In this paper, we present a comparative user study ( N=21) in which we investigated an audio-only condition compared to two levels of head-mounted display resolution ( 1832×1920 or 916×960 pixels per eye) and two levels of the native or visually enhanced appearance of a virtual human, the latter consisting of an up-scaled facial representation and simulated lipstick (lip coloring) added to increase contrast. To understand effects on speech perception in noise, we measured participants' speech reception thresholds (SRTs) for each audio-visual stimulus condition. These thresholds indicate the decibel levels of the speech signal that are necessary for a listener to receive the speech correctly 50% of the time. First, we show that the display resolution significantly affected participants' ability to perceive the speech signal in noise, which has practical implications for the field, especially in social virtual environments. Second, we show that our visual enhancement method was able to compensate for limited display resolution and was generally preferred by participants. Specifically, our participants indicated that they benefited from the head scaling more than the added facial contrast from the simulated lipstick. We discuss relationships, implications, and guidelines for applications that aim to leverage such enhancements.

New Generation of Benzidine Wide-Gap Conjugated Materials: Solution Processing a Classic Evaporated Scaffold.

Carbazole- and fluorene-substituted benzidine blocks have been functionalized with two different solubilizing pendant groups, in order to enhance the material's solubility in greener solvents. Preserving the optical and electrochemical properties, the aromatic function and substitution showed an important influence on the solvent affinity, achieving concentrations up to 150 mg/mL in o-xylenes for the glycol-containing materials and decent solubility in alcohols for the compounds functionalized with ionic chains. The latter solution proved to be ideal for the preparation of luminescence slot-die coating film on top of flexible-substrates up to 33 cm×2 cm. As a proof of concept, the materials have been implemented in different organic electronic devices, highlighting the low turn-on voltage (4 V) presented by organic light-emitting diodes (OLEDs), which is comparable with vacuum-processed devices. A structure-solubility relationship and a synthetic strategy are disentangled in this manuscript to tailor organic semiconductors and adapt their solubility towards the desired solvent and application.

Analysis of the Saliency of Color-Based Dichoptic Cues in Optical See-Through Augmented Reality.

In a future of pervasive augmented reality (AR), AR systems will need to be able to efficiently draw or guide the attention of the user to visual points of interest in their physical-virtual environment. Since AR imagery is overlaid on top of the user's view of their physical environment, these attention guidance techniques must not only compete with other virtual imagery, but also with distracting or attention-grabbing features in the user's physical environment. Because of the wide range of physical-virtual environments that pervasive AR users will find themselves in, it is difficult to design visual cues that "pop out" to the user without performing a visual analysis of the user's environment, and changing the appearance of the cue to stand out from its surroundings. In this article, we present an initial investigation into the potential uses of dichoptic visual cues for optical see-through AR displays, specifically cues that involve having a difference in hue, saturation, or value between the user's eyes. These types of cues have been shown to be preattentively processed by the user when presented on other stereoscopic displays, and may also be an effective method of drawing user attention on optical see-through AR displays. We present two user studies: one that evaluates the saliency of dichoptic visual cues on optical see-through displays, and one that evaluates their subjective qualities. Our results suggest that hue-based dichoptic cues or "Forbidden Colors" may be particularly effective for these purposes, achieving significantly lower error rates in a pop out task compared to value-based and saturation-based cues.

Scalable Non-Halogenated Co-solvent System for Large-Area, Four-Layer Slot-Die-Coated Organic Photovoltaics.

Sustainable processing solvents, photoactive materials, and scalable manufacturing will play a key role in commercializing printed organic photovoltaics (OPVs). The record-breaking pioneering OPV reports have done an outstanding job in accelerating the discovery of champion photoactive materials and device engineering practices; however, these works predominantly involve health-hazardous halogenated processing solvents/additives and non-scalable thin-film coating methods. Herein, large-area slot-die-manufactured OPV cells from eco-friendly halogen-free solvents and synthetically scalable materials are showcased. All the four layers; electron transport layer (SnO2), cathode interlayer (PDIN-H), bulk-heterojunction (BHJ, PTQ-10:BTP-4F-12), and hole transport layer [poly(3,4-ethylenedioxythiophene):polystyrene sulfonate) (PEDOT:PSS] are slot-die-coated in air. A non-halogenated co-solvent mixture of toluene and 2-methyl tetrahydrofuran is presented as an optimal processing solvent to realize the high-quality thin films of PTQ10:BTP-4F-12. The unencapsulated champion solar cells characterized in ambient conditions (RH = 30%, T = 22 °C) exhibit power conversion efficiencies (PCEs) of 12.1 and 17.8% under 1 Sun (100 mW/cm2) and indoor light-emitting diode lighting (580 µW/cm2) conditions, respectively. Additionally, PEDOT:PSS is successfully slot-die-coated atop BHJ by mitigating wettability challenges with the aid of surface treatment. The all four-layer slot-die-coated OPVs exhibit a PCE of 9.55%.

New Perylene Diimide Ink for Interlayer Formation in Air-Processed Conventional Organic Photovoltaic Devices.

Roll-to-roll coating of conventional organic photovoltaic architectures in air necessitates low work function, electron-harvesting interlayers as the top interface, termed cathode interlayers. Traditional materials based on metal oxides are often not compatible with coating in air and/or green solvents, require thermal annealing, and are limited in feasibility due to interactions with underlying layers. Alternatively, perylene diimide materials offer easily tunable redox properties, are amenable to air coating in green solvents, and are considered champion organic-based cathode interlayers. However, underlying mechanisms of the extraction of photogenerated electrons are less well understood. Herein, we demonstrate the utilization of two N-annulated perylene diimide materials, namely, PDIN-H and CN-PDIN-H, in air-processed conventional organic photovoltaic devices, using the now standard PM6:Y6 photoactive layer. The processing ink formulation using cesium carbonate as a processing agent to solubilize the perylene diimides in suitable green solvents (1-propanol and ethyl acetate) for uniform film formation using spin or slot-die coating on top of the photoactive layer is critical. Cesium carbonate remains in the film, creating hybrid organic/metal salt cathode interlayers. Best organic photovoltaic devices have power conversion efficiencies of 13.2% with a spin-coated interlayer and 13.1% with a slot-die-coated interlayer, superior to control devices using the classic conjugated polyelectrolyte PFN-Br as an interlayer (ca. 12.8%). The cathode interlayers were found to be semi-insulating in nature, and the device performance improvements were attributed to beneficial interfacial effects and electron tunneling through sufficiently thin layers. The efficiencies beyond 13% achieved in air-processed organic photovoltaic devices utilizing slot-die-coated cathode interlayers are among the highest reported so far, opening new opportunities for the fabrication of large-area solar cell modules.

Development of Tetrameric N-Annulated Perylene Diimides Using "Click" Chemistry.

Herein, we report the design, synthesis, and characterization of two novel N-annulated perylene diimide (NPDI) tetramer arrays that were developed using copper catalyzed alkyne-azide cycloaddition. Despite the optoelectronic properties of both tetramers being nearly identical, the two tetramers exhibited very different molecular geometries. The twisted spirobifluorene NPDI tetramer (sbfNPDI4 ) was found to have an extended and flexible geometry, while the planar pyrene NPDI tetramer (pyrNPDI4 ) exhibited a highly congested and conformationally locked geometry. Organic photovoltaic devices were constructed to demonstrate the use of both new compounds as electron acceptor materials, where slightly higher power conversion efficiencies were achieved with pyrNPDI4 than sbfNPDI4 . This study highlights the viability of using "click" chemistry as a facile synthetic strategy towards the development of new multicomponent perylene diimide materials for organic electronic applications.

Promoting photocatalytic CO2 reduction through facile electronic modification of N-annulated perylene diimide rhenium bipyridine dyads.

The development of CO2 conversion catalysts has become paramount in the effort to close the carbon loop. Herein, we report the synthesis, characterization, and photocatalytic CO2 reduction performance for a series of N-annulated perylene diimide (NPDI) tethered Re(bpy) supramolecular dyads [Re(bpy-C2-NPDI-R)], where R = -H, -Br, -CN, -NO2, -OPh, -NH2, or pyrrolidine (-NR2). The optoelectronic properties of these Re(bpy-C2-NPDI-R) dyads were heavily influenced by the nature of the R-group, resulting in significant differences in photocatalytic CO2 reduction performance. Although some R-groups (i.e. -Br and -OPh) did not influence the performance of CO2 photocatalysis (relative to -H; TONco ∼60), the use of an electron-withdrawing -CN was found to completely deactivate the catalyst (TONco < 1) while the use of an electron-donating -NH2 improved CO2 photocatalysis four-fold (TONco = 234). Despite being the strongest EWG, the -NO2 derivative exhibited good photocatalytic CO2 reduction abilities (TONco = 137). Using a combination of CV and UV-vis-nIR SEC, it was elucidated that the -NO2 derivative undergoes an in situ transformation to -NH2 under reducing conditions, thereby generating a more active catalyst that would account for the unexpected activity. A photocatalytic CO2 mechanism was proposed for these Re(bpy-C2-NPDI-R) dyads (based on molecular orbital descriptions), where it is rationalized that the photoexcitation pathway, as well as the electronic driving-force for NPDI2- to Re(bpy) electron-transfer both significantly influence photocatalytic CO2 reduction. These results help provide rational design principles for the future development of related supramolecular dyads.

3D Nanoscale Morphology Characterization of Ternary Organic Solar Cells.

It is highly desired to develop advanced characterization techniques to explore the 3D nanoscale morphology of the complicated blend film of ternary organic solar cells (OSCs). Here, ternary OSCs are constructed by incorporating the nonfullerene acceptor perylenediimide (PDI)-diketopyrrolopyrrole (DPP)-PDI and their morphology is characterized in depth to understand the performance variation. In particular, photoinduced force microscopy (PiFM) coupled with infrared laser spectroscopy is conducted to qualitatively study the distribution of donor and acceptors in the blend film by chemical identification and to quantitatively probe the segmentation of domains and the domain size distribution after PDI-DPP-PDI acceptor incorporation by PiFM imaging and data processing. In addition, the energy-filtered transmission electron microscopy with energy loss spectra is utilized to visualize the nanoscale morphology of ultrathin cross-sections in the configuration of the real ternary device for the first time in the field of photovoltaics. These measurements allow to "view" the surface and cross-sectional morphology and provide strong evidence that the PDI-DPP-PDI acceptor can suppress the aggregation of the fullerene molecules and generate the homogenous morphology with a higher-level of the molecularly mixed phase, which can prevent the charge recombination and stabilize the morphology of photoactive layer.

Green Solvent-Processible N-H-Functionalized Perylene Diimide Materials for Scalable Organic Photovoltaics.

The growing demand for organic electronic devices warrants further development of the scalability and green solvent processibility of π-conjugated materials. Perylene diimide (PDI)-based materials have shown impressive performance as interlayers for electronic devices due to a low ELUMO energy and high charge mobility in films. The next step in the development of these materials is the transition toward scalable production and the fabrication of devices under ambient conditions. Here, we develop a green synthetic methodology to prepare a series of PDI-based electronically active materials (X2-5), which can be slot-die-coated into uniform thin films from green solvents in air. Compounds X2-5 comprised a monomeric PDI core with a functional cyclic secondary amine appended to the bay region. Bromine or cyano moieties are incorporated into the molecular scaffold to systematically tune optoelectronic properties. The utility of these materials is demonstrated by slot-die coating them from ethanol to serve as cathode interlayers in prototype air-processed conventional organic photovoltaics. Using a PM6:Y6 active layer, device power conversion efficiencies reached 10%, among the best reported under these conditions.

Tin Oxide Electron Transport Layers for Air-/Solution-Processed Conventional Organic Solar Cells.

Commercialization of organic solar cells (OSC) is imminent. Interlayers between the photoactive film and the electrodes are critical for high device efficiency and stability. Here, the applicability of SnO2 nanoparticles (SnO2 NPs) as the electron transport layer (ETL) in conventional OSCs is evaluated. A commercial SnO2 NPs solution in butanol is mixed with ethanol (EtOH) as a processing co-solvent to improve film formation for spin and slot-die coating deposition procedures. When processed with 200% v/v EtOH, the SnO2 NPs film presents uniform film quality and low photoactive layer degradation. The optimized SnO2 NPs ink is coated, in air, on top of two polymer:fullerene-based systems and a nonfullerene system, to form an efficient ETL film. In every case, addition of SnO2 NPs film significantly enhances photovoltaic performance, from 3.4 and 3.7% without the ETL to 6.0 and 5.7% when coated on top of PBDB-T:PC61BM and PPDT2FBT:PC61BM, respectively, and from 3.7 to 7.1% when applied on top of the PTQ10:IDIC system. Flexible, all slot-die-coated devices, in air, are also fabricated and tested, demonstrating the versatility of the SnO2 NPs ink for efficient ETL formation on top of organic photoactive layers, processed under ambient condition, ideal for practical large-scale production of OSCs.

Zinc Oxide-Perylene Diimide Hybrid Electron Transport Layers for Air-Processed Inverted Organic Photovoltaic Devices.

In this work, we report the formation of perylene diimide films, from green solvents, for use as electron transporting layers, when combined with ZnO, in inverted-type organic photovoltaics. A modified N-annulated PDI was functionalized with a tert-butyloxycarbonyl protecting group to solubilize the material, enabling solution processing from green solvents. Post-deposition treatment of films via thermal annealing cleaves the protecting group yielding the known PDIN-H material, rendering films solvent-resistant. The PDIN-H films were characterized by optical absorption spectroscopy, contact angle measurements, and atomic force microscopy. When used to modify the surface of ZnO in inverted-type organic photovoltaics (air-processed and tested) based on the PM6:Y6 and PTQ10:Y6 bulk-heterojunctions, the device power conversion efficiency increases from 9.8 to 11.0% and 7.2 to 9.8%, respectively.

Lowering Electrocatalytic CO2 Reduction Overpotential Using N-Annulated Perylene Diimide Rhenium Bipyridine Dyads with Variable Tether Length.

We report the design, synthesis, and characterization of four N-annulated perylene diimide (NPDI) functionalized rhenium bipyridine [Re(bpy)] supramolecular dyads. The Re(bpy) scaffold was connected to the NPDI chromophore either directly [Re(py-C0-NPDI)] or via an ethyl [Re(bpy-C2-NPDI)], butyl [Re(bpy-C4-NPDI)], or hexyl [Re(bpy-C6-NPDI)] alkyl-chain spacer. Upon electrochemical reduction in the presence of CO2 and a proton source, Re(bpy-C2/4/6-NPDI) all exhibited significant current enhancement effects, while Re(py-C0-NPDI) did not. During controlled potential electrolysis (CPE) experiments at Eappl = -1.8 V vs Fc+/0, Re(bpy-C2/4/6-NPDI) all achieved comparable activity (TONco ∼ 25) and Faradaic efficiency (FEco ∼ 94%). Under identical CPE conditions, the standard catalyst Re(dmbpy) was inactive for electrocatalytic CO2 reduction; only at Eappl = -2.1 V vs Fc+/0 could Re(dmbpy) achieve the same catalytic performance, representing a 300 mV lowering in overpotential for Re(bpy-C2/4/6-NPDI). At higher overpotentials, Re(bpy-C4/6-NPDI) both outperformed Re(bpy-C2-NPDI), indicating the possibility of coinciding electrocatalytic CO2 reduction mechanisms that are dictated by tether-length and overpotential. Using UV-vis-nearIR spectroelectrochemistry (SEC), FTIR SEC, and chemical reduction experiments, it was shown that the NPDI-moiety served as an electron-reservoir for Re(bpy), thereby allowing catalytic activity at lower overpotentials. Density functional theory studies probing the optimized geometries and frontier molecular orbitals of various catalytic intermediates revealed that the geometric configuration of NPDI relative to the Re(bpy)-moiety plays a critical role in accessing electrons from the electron-reservoir. The improved performance of Re(bpy-C2/4/6-NPDI)dyads at lower overpotentials, relative to Re(dmbpy), highlights the utility of chromophore electron-reservoirs as a method for lowering the overpotential for CO2 conversion.

Hybrid Tetrameric Perylene Diimide Assemblies.

Organic photovoltaics have found utility as indoor light recycling devices providing an opportunity for the sustainable powering of IoT sensors and related smart electronics. In the report, two organic π-conjugated molecules consisting of four perylene diimide (PDI) chromophores each are presented and used as non-fullerene acceptors in indoor photovoltaic devices. The new materials consist of a dimeric N-annulated PDI core with single PDIs grafted onto the pyrrolic N-atom positions of the core. Compounds PDI4 e and PDI4 i are PDI tetramers and differ with PDI4 e having the terminal N-annulated PDI with pyrrolic N-atom distal to the core and PDI4 i having the terminal N-annulated PDI with pyrrolic N-atom proximal to the core. The structural and optoelectronic properties were investigated using NMR spectroscopy, optical absorption and emission spectroscopy, and cyclic voltammetry. The compounds exhibit typical optical signatures for PDIs but notable is that the addition of grafted PDI molecules prevents significant aggregation of the dimeric PDI core, as compared to a reference dimer. Use as non-fullerene acceptors in ternary bulk-heterojunction blends with the polymer FBT and fullerene PC61 BM lead to increased open-circuit voltages and power conversion efficiencies upwards of 13.7 % at 2000 lux light intensity.

Mixed Reality Tabletop Gameplay: Social Interaction With a Virtual Human Capable of Physical Influence.

In this article, we investigate the effects of the physical influence of a virtual human (VH) in the context of face-to-face interaction in a mixed reality environment. In Experiment 1, participants played a tabletop game with a VH, in which each player takes a turn and moves their own token along the designated spots on the shared table. We compared two conditions as follows: the VH in the virtual condition moves a virtual token that can only be seen through augmented reality (AR) glasses, while the VH in the physical condition moves a physical token as the participants do; therefore the VH's token can be seen even in the periphery of the AR glasses. For the physical condition, we designed an actuator system underneath the table. The actuator moves a magnet under the table which then moves the VH's physical token over the surface of the table. Our results indicate that participants felt higher co-presence with the VH in the physical condition, and participants assessed the VH as a more physical entity compared to the VH in the virtual condition. We further observed transference effects when participants attributed the VH's ability to move physical objects to other elements in the real world. Also, the VH's physical influence improved participants' overall experience with the VH. In Experiment 2, we further looked into the question how the physical-virtual latency in movements affected the perceived plausibility of the VH's interaction with the real world. Our results indicate that a slight temporal difference between the physical token reacting to the virtual hand's movement increased the perceived realism and causality of the mixed reality interaction. We discuss potential explanations for the findings and implications for future shared mixed reality tabletop setups.

Reducing Cognitive Load and Improving Warfighter Problem Solving With Intelligent Virtual Assistants.

Recent times have seen increasing interest in conversational assistants (e.g., Amazon Alexa) designed to help users in their daily tasks. In military settings, it is critical to design assistants that are, simultaneously, helpful and able to minimize the user's cognitive load. Here, we show that embodiment plays a key role in achieving that goal. We present an experiment where participants engaged in an augmented reality version of the relatively well-known desert survival task. Participants were paired with a voice assistant, an embodied assistant, or no assistant. The assistants made suggestions verbally throughout the task, whereas the embodied assistant further used gestures and emotion to communicate with the user. Our results indicate that both assistant conditions led to higher performance over the no assistant condition, but the embodied assistant achieved this with less cognitive burden on the decision maker than the voice assistant, which is a novel contribution. We discuss implications for the design of intelligent collaborative systems for the warfighter.

Atomic Precision Graphene Model Compound for Bright Electrochemiluminescence and Organic Light-Emitting Diodes.

An N-annulated perylene diimide dimer, tPDI2N-hex, a graphene model compound with atomic precision, was investigated for luminescence applications. Electrochemiluminescence (ECL) of tPDI2N-hex was studied with tri-n-propylamine (TPrA) as a reducing coreactant. ECL-voltage curves along with spooling ECL spectra provided details of light generation mechanisms. The relative ECL quantum efficiency of the Ru(bpy)3(PF6)2/TPrA system was calculated to be 64%, which is superior to that of many other organic molecules because of the desired excited state in the absence of surface states. An organic light-emitting diode (OLED) fabricated with tPDI2N-hex displayed bright orange-red emission with a low color temperature, which is very desirable. It is plausible that the sterically constrained and thus orthogonal aromatic moieties in the tPDI2N-hex structure, with atomic precision graphene layer characteristics, lead to the excellent luminescence performances. The ECL and OLED studies of tPDI2N-hex showcase great application potentials of tPDI2N-hex in both solution-based ECL probes and solid-state light devices.

Slot-Die-Coated Ternary Organic Photovoltaics for Indoor Light Recycling.

Efficient organic photovoltaics (OPVs) based on slot-die-coated (SD) ternary blends were developed for low-intensity indoor light harvesting. For active layers processed in air and from eco-friendly solvents, our device performances (under 1 sun and low light intensity) are the highest reported values for fluoro-dithiophenyl-benzothiadiazole donor polymer-based OPVs. The N-annulated perylene diimide dimer acceptor was incorporated into a blend of donor polymer (FBT) and fullerene acceptor (PC61BM) to give ternary bulk heterojunction blends. SD ternary-based devices under 1 sun illumination showed enhanced power conversion efficiency (PCE) from 6.8 to 7.7%. We observed enhancement in the short-circuit current density and open-circuit voltage of the devices. Under low light intensity light-emitting device illumination (ca. 2000 lux), the ternary-based devices achieved a PCE of 14.0% and a maximum power density of 79 µW/cm2 compared to a PCE of 12.0% and a maximum power density of 68 µW/cm2 for binary-based devices. Under the same illumination conditions, the spin-coated (SC) devices showed a PCE of 15.5% and a maximum power density of 88 µW/cm2. Collectively, these results demonstrate the exceptional promise of a SD ternary blend system for indoor light harvesting and the need to optimize active layers based on industry-relevant coating approaches toward mini modules.

Synthesis, characterization and use of benzothioxanthene imide based dimers.

The synthesis of benzothioxanthene imide based dimers is reported herein. Subtle chemical modifications were carried out and their impact on the optical and electrochemical properties was investigated for a better structure-property relationship analysis. The icing on the cake was that these new structures were used as light emitting materials for the fabrication and demonstration of the first BTXI-based OLEDs.

Assessing Fall Risk Appraisal Through Combined Physiological and Perceived Fall Risk Measures Using Innovative Technology.

The current study aimed to categorize fall risk appraisal and quantify discrepancies between perceived fall risk measured subjectively using the short Fall Efficacy Scale-International and physiological fall risk measured objectively using the portable BTrackS™ Assess Balance System. One hundred two community-dwelling older adults were evaluated in this cross-sectional study. Approximately 40% of participants had maladaptive fall risk appraisals, which were either irrational (high perceived risk despite low physiological fall risk) or incongruent (low perceived risk but high physiological fall risk). The remaining 60% of participants had adaptive fall risk appraisals, which were either rational (low perceived risk aligned with low physiological fall risk) or congruent (high perceived risk aligned with high physiological fall risk). Among participants with rational, congruent, irrational, and incongruent appraisals, 21.7%, 66.7%, 28%, and 18.8%, respectively, reported having a history of falls (p < 0.01). Using technology to identify discrepancies in perceived and physiological fall risks can potentially increase the success of fall risk screening and guide fall interventions to target perceived or physiological components of balance. [Journal of Gerontological Nursing, 46(4), 41-47.].