Interface Engineering Improves the Performance of Green Perovskite Light-emitting Diodes

To realize high-performance perovskite light-emitting diodes (PeLEDs), the underlying charge transport layer plays a vital role in charge injection and perovskite growth. Herein, a rational interface engineering method has been...

Defects and passivation in perovskite solar cells

This organic-inorganic hybrid perovskite materials have attracted great attention by virtue of their high absorption coefficient, low cost and simple film deposition technique. Based on these advantages, perovskite solar cells have reached an impressive power conversion efficiency over 25%. However, the low-temperature process inevitably leads to a large number of defects in the perovskite film. These defects would exacerbate the carrier recombination, induce crystal degradation, phase transformation and seriously affect the performance of devices. Studying the defects in perovskite film is of great significance for the development of high-performance perovskite solar cells. Herein, the authors summarise the causes, distribution and features of defects, as well as their effects on the performance of perovskite solar cells. Furthermore, some defect-passivation strategies on perovskite film or the device, including grain boundary passivation, surface passivation, capping layer modification and charge transport layer passivation, are discussed, respectively. Lastly, some remaining challenges in the commercialisation of perovskite solar cells are proposed.

On-Surface Synthesis of Variable Bandgap Nanoporous Graphene

<p>Tuning the bandgap of nanoporous graphene is desirable for applications such as the charge transport layer in organic-hybrid devices. The holy grail in the field is the ability to synthesize 2D nanoporous graphene with variable pore sizes, and hence tuneable band gaps. Herein, we demonstrate the on-surface synthesis of nanoporous graphene with variable bandgaps. Two types of nanoporous graphene were synthesized via hierarchical C-C coupling, and verified by low-temperature scanning tunneling microscopy and non-contact atomic force microscopy with CO-terminated tip. Nanoporous graphene-1 is non-planar, and nanoporous graphene-2 is a single-atom thick planar sheet. Scanning tunneling spectroscopy measurements reveal that nanoporous graphene-2 has a bandgap of 3.8 eV, while nanoporous graphene-1 has a larger bandgap of 5.0 eV. Corroborated by first-principles calculations, we propose that the large bandgap opening is governed by the confinement of π-electrons induced by pore generation or the non-planar structure, and can be explained by Clar sextet theory. Our finding shows that by introducing nanopores, semimetallic graphene is converted into semiconducting nanoporous graphene-2 or insulating wide-bandgap nanoporous graphene-1. </p><br>

On-Surface Synthesis of Variable Bandgap Nanoporous Graphene

<p>Tuning the bandgap of nanoporous graphene is desirable for applications such as the charge transport layer in organic-hybrid devices. The holy grail in the field is the ability to synthesize 2D nanoporous graphene with variable pore sizes, and hence tuneable band gaps. Herein, we demonstrate the on-surface synthesis of nanoporous graphene with variable bandgaps. Two types of nanoporous graphene were synthesized via hierarchical C-C coupling, and verified by low-temperature scanning tunneling microscopy and non-contact atomic force microscopy with CO-terminated tip. Nanoporous graphene-1 is non-planar, and nanoporous graphene-2 is a single-atom thick planar sheet. Scanning tunneling spectroscopy measurements reveal that nanoporous graphene-2 has a bandgap of 3.8 eV, while nanoporous graphene-1 has a larger bandgap of 5.0 eV. Corroborated by first-principles calculations, we propose that the large bandgap opening is governed by the confinement of π-electrons induced by pore generation or the non-planar structure, and can be explained by Clar sextet theory. Our finding shows that by introducing nanopores, semimetallic graphene is converted into semiconducting nanoporous graphene-2 or insulating wide-bandgap nanoporous graphene-1. </p><br>

Merged interface construction toward ultra-low Voc loss in inverted two-dimensional Dion-Jacobson perovskite solar cells with efficiency over 18%

Optimized interface between perovskite and the charge transport layer with full contact and low defect density favored the performance improvement of perovskite solar cells (PVSCs). However, few works have been...