7,984 research outputs found
Addressing the stability issue of perovskite solar cells for commercial applications.
Abstract When translating photovoltaic technology from laboratory to commercial products, low cost, high power conversion efficiency, and high stability (long lifetime) are the three key metrics to consider in addition to other factors, such as low toxicity, low energy payback time, etc. As one of the most promising photovoltaic materials with high efficiency, today organic–inorganic metal halide perovskites draw tremendous attention from fundamental research, but their practical relevance still remains unclear owing to the notorious short device operation time. In this comment, we discuss the stability issue of perovskite photovoltaics and call for standardized protocols for device characterizations that could possibly match the silicon industrial standards
Classification of Symmetry-Protected Phases for Interacting Fermions in Two Dimensions
Recently, it has been shown that two-dimensional bosonic symmetry-protected
topological(SPT) phases with on-site unitary symmetry can be completely
classified by the group cohomology class . Later, group
super-cohomology class was proposed as a partial classification for SPT phases
of interacting fermions. In this work, we revisit this problem based on the
mathematical framework of -extension of unitary braided tensor
category(UBTC) theory. We first reproduce the partial classifications given by
group super-cohomology, then we show that with an additional structure, a complete classification of SPT phases for
two-dimensional interacting fermion systems for a total symmetry group
can be achieved. We also discuss the classification of
interacting fermionic SPT phases protected by time-reversal symmetry.Comment: references added; published versio
Decoupling Dynamic Monocular Videos for Dynamic View Synthesis
The challenge of dynamic view synthesis from dynamic monocular videos, i.e.,
synthesizing novel views for free viewpoints given a monocular video of a
dynamic scene captured by a moving camera, mainly lies in accurately modeling
the dynamic objects of a scene using limited 2D frames, each with a varying
timestamp and viewpoint. Existing methods usually require pre-processed 2D
optical flow and depth maps by off-the-shelf methods to supervise the network,
making them suffer from the inaccuracy of the pre-processed supervision and the
ambiguity when lifting the 2D information to 3D. In this paper, we tackle this
challenge in an unsupervised fashion. Specifically, we decouple the motion of
the dynamic objects into object motion and camera motion, respectively
regularized by proposed unsupervised surface consistency and patch-based
multi-view constraints. The former enforces the 3D geometric surfaces of moving
objects to be consistent over time, while the latter regularizes their
appearances to be consistent across different viewpoints. Such a fine-grained
motion formulation can alleviate the learning difficulty for the network, thus
enabling it to produce not only novel views with higher quality but also more
accurate scene flows and depth than existing methods requiring extra
supervision
- …