Take a look at the great cover images from the April issues and top five most downloaded articles this month.

Cover by Aleksandra B. Djurišić and co-workers

Issue 7

Perovskite Solar Cells

In article number 1502206, Aleksandra B. Djurišić and co-workers discuss whether excess PbI₂ is beneficial for perovskite solar cell performance. The presence of unreacted PbI₂ is commonly believed to be beneficial to the efficiency of perovskite solar cells. However, it results in an intrinsic instability of the illuminated film even in inert atmosphere, leading to accelerated film degradation under illumination.

Cover by Il-Kwon Oh and co-workers

Issue 8

Nanofibers

In article number 1502329, Il-Kwon Oh and co-workers demonstrate an eco-friendly silk nanofiber-networked bio-triboelectric generator (Silk Bio-TEG) based on an electrospun nanofiber-networked film. Using an eco-friendly and sustainable bio-material and simple fabrication processes, this Silk Bio-TEG has great potential for self-powered systems even under environments of harsh vibration, and in living organisms with no harmful effects.

Top five most downloaded papers:

A Novel Aluminum–Graphite Dual‐Ion Battery

by Xiaolong Zhang, Yongbing Tang, Fan Zhang and Chun-Sing Lee

Air‐Stable, Efficient Mixed‐Cation Perovskite Solar Cells with Cu Electrode by Scalable Fabrication of Active Layer

by Yehao Deng, Qingfeng Dong, Cheng Bi, Yongbo Yuan and Jinsong Huang

3D Vertically Aligned and Interconnected Porous Carbon Nanosheets as Sulfur Immobilizers for High Performance Lithium-Sulfur Batteries

by Sarish Rehman, Xingxing Gu, Kishwar Khan, Nasir Mahmood, Wenlong Yang, Xiaoxiao Huang, Shaojun Guo, and Yanglong Hou

Wet-Chemical Processing of Phosphorus Composite Nanosheets for High-Rate and High-Capacity Lithium-Ion Batteries

by Yanyan Zhang, Xianhong Rui, Yuxin Tang, Yaqing Liu, Jiaqi Wei, Shi Chen, Wan Ru Leow, Wenlong Li, Yuanjun Liu, Jiyang Deng, Bing Ma, Qingyu Yan and Xiaodong Chen

3D Porous Hierarchical Nickel–Molybdenum Nitrides Synthesized by RF Plasma as Highly Active and Stable Hydrogen-Evolution-Reaction Electrocatalysts

by Yongqi Zhang, Bo Ouyang, Jing Xu, Shi Chen, Rajdeep Singh Rawat, and Hong Jin Fan