Indoor photovoltaics, the next big trend in solution-processed solar cells

Indoor photovoltaics (IPVs) have attracted considerable interest for their potential to power small and portable electronics and photonic devices. The recent advancemes in circuit design and device optimizations has led to the power required to operate electronics for the internet of things (IoT), such as distributed sensors, remote actuators, and communication devices, being remarkably reduced. Therefore, various types of sensors and a large number of nodes can be wireless or even batteryless powered by IPVs. In this review, we provide a comprehensive overview of the recent developments in IPVs. We primarily focus on third‐generation solution‐processed solar cell technologies, which include organic solar cells, dye‐sensitized solar cells, perovskite solar cells, and newly developed colloidal quantum dot indoor solar cells. Besides, the device design principles are also discussed in relation to the unique characteristics of indoor lighting conditions. Challenges and prospects for the development of IPV are also summarized, which, hopefully, can lead to a better understanding of future IPV design as well as performance enhancement

Tailoring Carbon Nanostructure for High Frequency Supercapacitor Operation

The possibility of enhancing the frequency performance of electrochemical capacitors by tailoring the nanostructure of the carbon electrode to increase electrolyte permeability is demonstrated. Highly porous, vertically oriented carbon electrodes which are in direct electrical contact with the metallic current collector are produced via MPECVD growth on metal foils. The resulting structure has a capacitance and frequency performance between that of an electrolytic capacitor and an electrochemical capacitor. Fully packaged devices are produced on Ni and Cu current collectors and performance compared to state-of-the-art electrochemical capacitors and electrolytic capacitors. The extension of capacitive behavior to the AC regime (~100 Hz) opens up an avenue for a number of new applications where physical volume of the capacitor may be significantly reduced

Solution-processed colloidal quantum dots for light emission

Quantum dots (QDs) are an emerging class of photoactive materials that exhibit extraordinary optical features. Due to the availability of narrowband emitted light from QDs, they can be used to pave the way for next-generation light-emitting devices, especially in the development of LEDs and lasers. Over recent years solution-processed colloidal QDs have been developed in pre-existing light-emitting devices such as laser scalpels, displays and data communications. QDs became mainstream in 2013, with Sony and Samsung launching QD televisions, in which photo emissive QDs are used in the backlight of LCD TVs to replace red and green phosphors. Currently, photo-emissive QD displays are the only commercially available large area QD display, with electro-emissive displays limited to smaller sizes in some smartphone devices. At the same time, lighting now accounts for 15 to 22% of the electricity used in developed countries. This highlights how fundamental artificial lighting is to humans and why more efficient light sources can significantly impact energy consumption. Throughout history, any progress in artificial lighting (with regards to chemical sources and physical phenomena) has been to increase efficiency, improve light quality and decrease costs. QDs offer this capability to advance current lighting solutions. However, even with the advancements in QD performance, there remain issues with creating heavy metal-free high-performance QD devices. This paper presents a review of colloidal QD synthesis and the reasons behind their use in light emission applications

Electrical transport between epitaxial manganites and carbon nanotubes

The possibility of performing spintronics at the molecular level may be realized in devices that combine fully spin polarized oxides such as manganites with carbon nanotubes. However, it is not clear whether electrical transport between such different material systems is viable. Here we show that the room temperature conductance of manganite-nanotube-manganite devices is only half the value recorded in similar palladium-nanotube-palladium devices. Interestingly, the former shows a pseudogap in the conductivity below the relatively high temperature of 200 K. Our results suggest the possibility of new spintronics heterostructures that exploit fully spin polarized sources and drains