Semitransparent perovskite solar cells are prepared by laminating graphene transparent electrodes on the top for the first time. The device performance is optimized by improving the conductivity of the graphene electrodes and the contact between the graphene and the perovskite active layers during the lamination process. The devices show high power conversion efficiencies when they are illuminated from both sides.

The performance of organic solar cells is substantially enhanced by introducing high-mobility conjugate polymers as additives for the first time. The most pronounced effect is observed in one type of device with the average power conversion efficiencies increased from 8.75% to 10.08% after the addition of a high-mobility polymer for only 0.5 weight percent in the active layers, which is mainly attributed to the increased hole mobility and carrier lifetime in the devices. Besides the hole mobility, the energy band structure of the additive is also found to be critical to the enhancement of the device performance. This work demonstrates a novel approach for improving the efficiencies of organic solar cells.

2D van der Waals crystals, possessing excellent electronic and physical properties, have been intriguing building blocks for organic optoelectronic devices. Most of the 2D materials are served as hole transport layers in organic devices. Here,it is reported that solution exfoliated few layers black phosphorus (BP) can be served as an effective electron transport layer (ETL) in organic photovoltaics (OPVs) for the first time. The power conversion efficiencies (PCEs) of the BP‐incorporated OPVs can be improved to 8.18% in average with the relative enhancement of 11%. The incorporation of BP flakes with the optimum thickness of ≈10 nm can form cascaded band structure in OPVs, which can facilitate electron transport and enhance the PCEs of the devices. This study opens an avenue in using solution exfoliated BP as a highly efficient ETL for organic optoelectronics.

During the past two decades, the vigorous development of flexible organic semiconductor devices has heralded a new era of human society due to their promising applications in portable, wearable, implantable, and biological electronics. In recent years, exciting progress has been made on various flexible electronic devices, including organic light‐emitting diodes, organic photovoltaics, organic thin‐film transistors, organic flexible integrated circuits, sensors, and memories. Here, to provide a comprehensive and up‐to‐date review on this emerging field, the focus is on the critical issues of organic devices, including material choice, device design, mechanical flexibility, strain effects, and processing techniques, as well as some specific applications that have been successfully developed. Finally, a conclusion and an outlook for the future development of this field are given.

PSS FTEs is also useful in many other types of flexible optoelectronic devices.

Graphene has been considered as a promising material for transparent electrodes due to its advantages including ultrahigh carrier mobilities, high optical transmittance, excellent mechanical flexibility, and good stability. Solar cells with all-graphene electrodes are potentially low-cost, high-performance, and environmental friendly, which however have not been realized until now. Here, we report the fabrication of semitransparent organic photovoltaics (OPVs) with graphene transparent electrodes as both cathode and anode, which can absorb light from both sides with the power conversion efficiency up to 3.4%. Meanwhile, the OPVs have a neutral color and show the transmittance of ∼40% in the visible region, making them suitable for some special applications, such as power-generating windows and building integrated photovoltaics. This work demonstrates the great potential of graphene for the applications in carbon-based optoelectronic devices.

Winding and rewinding: How many times can helical aromatic oligomers wind around one another? At least four, as judged by the aggregation behavior of oligoamides based on 8‐fluoroquinoline (see scheme depicting the formation of a quadruple helix; red spheres: sites in the hollow space partially occupied by water molecules).

Although organic photovoltaic devices (OPVs) have been investigated for more than two decades, the power conversion efficiencies of OPVs are much lower than those of inorganic or perovskite solar cells. One effective approach to improve the efficiency of OPVs is to introduce additives to enhance light harvesting as well as charge transportation in the devices. Here, black phosphorus quantum dots (BPQDs) are introduced in OPVs as an additive. By adding 0.055 wt % BPQDs relative to the polymer donors in the OPVs, the device efficiencies can be dramatically improved for more than 10 %. The weight percentage is much lower than that of any other additive used in OPVs before, which is mainly due to the two-dimentional structure as well as the strong broadband light absorption and scattering of the BPQDs. This work paves a way for using two-dimentional quantum dots in OPVs as a cost-effective approach to enhance device efficiencies.