penghuang

Abstract

Publication date: 30 August 2016
Source:Journal of Power Sources, Volume 324
Author(s): Lei Yang, Yusheng Chen, Shangshang Chen, Tao Dong, Wei Deng, Lei Lv, Saina Yang, He Yan, Hui Huang
Two analogous dimer and tetramer compounds, SF-PDI2 and SF-PDI4, were designed, theoretically calculated, synthesized, and developed as electron acceptors for organic solar cells. The effects of the number of the electron deficient building blocks on the optical absorption, energy levels, charge transport, morphology, crystallinity, and photovoltaic performance of the molecules were investigated. In combination with two different donors, PTB7-Th and PffBT4T-2OD, the results showed that increasing the numbers of PDI building blocks is beneficial to photovoltaic performance and leads to efficiency over 5%.

Graphical abstract

Publication date: 30 August 2016
Source:Journal of Power Sources, Volume 324
Author(s): Keeyoung Jung, Jeffrey P. Colker, Yuzhe Cao, Goun Kim, Yoon-Cheol Park, Chang-Soo Kim
We introduce a comprehensive finite-element analysis (FEA) computational model to accurately predict the thermo-mechanical stresses at heterogeneous joints and components of large-size sodium sulfur (NaS) cells during thermal cycling. Quantification of the thermo-mechanical stress is important because the accumulation of stress during cell assembly and/or operation is one of the critical issues in developing practical planar NaS cells. The computational model is developed based on relevant experimental assembly and operation conditions to predict the detailed stress field of a state-of-the-art planar NaS cell. Prior to the freeze-and-thaw thermal cycle simulation, residual stresses generated from the actual high temperature cell assembly procedures are calculated and implemented into the subsequent model. The calculation results show that large stresses are developed on the outer surface of the insulating header and the solid electrolyte, where component fracture is frequently observed in the experimental cell fabrication process. The impacts of the coefficients of thermal expansion (CTE) of glass materials and the thicknesses of cell container on the stress accumulation are also evaluated to improve the cell manufacturing procedure and to guide the material choices for enhanced thermo-mechanical stability of large-size NaS cells.

Graphical abstract

Article

Phonon scattering limits charge transport in perovskite solar cells, yet the interactions involved are still poorly understood. Here, Wright et al . show by photoluminescence measurements and first-principles calculations that longitudinal optical phonons dominate the electron-phonon coupling at room temperature.

Nature Communications doi: 10.1038/ncomms11755

Authors: Adam D. Wright, Carla Verdi, Rebecca L. Milot, Giles E. Eperon, Miguel A. Pérez-Osorio, Henry J. Snaith, Feliciano Giustino, Michael B. Johnston, Laura M. Herz

Article

Visual evidence for photo-induced ionic migration in perovskite films without contacts is lacking. Here, the authors use a unique combination of confocal photoluminescence microscopy and chemical imaging to correlate the local changes in photophysics with composition in CH 3 NH 3 PbI 3 films under illumination.

Nature Communications doi: 10.1038/ncomms11683

Authors: Dane W. deQuilettes, Wei Zhang, Victor M. Burlakov, Daniel J. Graham, Tomas Leijtens, Anna Osherov, Vladimir Bulović, Henry J. Snaith, David S. Ginger, Samuel D. Stranks