ABSTRACT
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
ABSTRACT
To improve the efficiency of perovskite solar cells, careful device design and tailored interface engineering are needed to enhance optoelectronic properties and the charge extraction process at the selective electrodes. Here, we use two-dimensional transition metal carbides (MXene Ti3C2Tx) with various termination groups (Tx) to tune the work function (WF) of the perovskite absorber and the TiO2 electron transport layer (ETL), and to engineer the perovskite/ETL interface. Ultraviolet photoemission spectroscopy measurements and density functional theory calculations show that the addition of Ti3C2Tx to halide perovskite and TiO2 layers permits the tuning of the materials' WFs without affecting other electronic properties. Moreover, the dipole induced by the Ti3C2Tx at the perovskite/ETL interface can be used to change the band alignment between these layers. The combined action of WF tuning and interface engineering can lead to substantial performance improvements in MXene-modified perovskite solar cells, as shown by the 26% increase of power conversion efficiency and hysteresis reduction with respect to reference cells without MXene.
ABSTRACT
BACKGROUND: Pain and post-traumatic stress disorder (PTSD) are frequently co-morbid in the aftermath of a traumatic event. Although several models attempt to explain the relationship between these two disorders, the mechanisms underlying the relationship remain unclear. The aim of this study was to investigate the relationship between each PTSD symptom cluster and pain over the course of post-traumatic adjustment. METHOD: In a longitudinal study, injury patients (n=824) were assessed within 1 week post-injury, and then at 3 and 12 months. Pain was measured using a 100-mm Visual Analogue Scale (VAS). PTSD symptoms were assessed using the Clinician-Administered PTSD Scale (CAPS). Structural equation modelling (SEM) was used to identify causal relationships between pain and PTSD. RESULTS: In a saturated model we found that the relationship between acute pain and 12-month pain was mediated by arousal symptoms at 3 months. We also found that the relationship between baseline arousal and re-experiencing symptoms, and later 12-month arousal and re-experiencing symptoms, was mediated by 3-month pain levels. The final model showed a good fit [chi2=16.97, df=12, p>0.05, Comparative Fit Index (CFI)=0.999, root mean square error of approximation (RMSEA)=0.022]. CONCLUSIONS: These findings provide evidence of mutual maintenance between pain and PTSD.
Subject(s)
Pain/epidemiology , Pain/psychology , Stress Disorders, Post-Traumatic/epidemiology , Stress Disorders, Post-Traumatic/psychology , Adolescent , Adult , Aged , Arousal/physiology , Chronic Disease , Comorbidity , Female , Humans , Male , Middle Aged , Pain/diagnosis , Pain Measurement , Severity of Illness Index , Surveys and Questionnaires , Young AdultABSTRACT
In addition to posttraumatic stress disorder (PTSD) many traumatized individuals also suffer from chronic pain. Understanding the development and maintenance of these two disorders and how they interact is of crucial importance for treatment. This article provides an overview of the current literature on mechanisms of development, maintenance and comorbidity of PTSD and chronic pain. Moreover the perpetual avoidance model and its implications for practical application are presented.
