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Concept: IBM


Active electronic implants are powered by primary batteries, which induces the necessity of implant replacement after battery depletion. This causes repeated interventions in a patients' life, which bears the risk of complications and is costly. By using energy harvesting devices to power the implant, device replacements may be avoided and the device size may be reduced dramatically. Recently, several groups presented prototypes of implants powered by subcutaneous solar cells. However, data about the expected real-life power output of subcutaneously implanted solar cells was lacking so far. In this study, we report the first real-life validation data of energy harvesting by subcutaneous solar cells. Portable light measurement devices that feature solar cells (cell area = 3.6 cm(2)) and continuously measure a subcutaneous solar cell’s output power were built. The measurement devices were worn by volunteers in their daily routine in summer, autumn and winter. In addition to the measured output power, influences such as season, weather and human activity were analyzed. The obtained mean power over the whole study period was 67 µW (=19 µW cm(-2)), which is sufficient to power e.g. a cardiac pacemaker.

Concepts: Measurement, Solar cell, Energy conversion, Energy conversion efficiency, Diode, IBM, P-n junction, Energy harvesting


Carbon nanotube-Si and graphene-Si solar cells have attracted much interest recently owing to their potential in simplifying manufacturing process and lowering cost compared to Si cells. Until now, the power conversion efficiency of graphene-Si cells remains under 10% and well below that of the nanotube-Si counterpart. Here, we involved a colloidal anti-reflection coating onto a monolayer graphene-Si solar cell, and enhanced the cell efficiency to 14.5% under standard illumination (air mass 1.5, 100 mW/cm2) with a stable anti-reflection effect over long time. The anti-reflection treatment was realized by a simple spin-coating process, which significantly increased the short-circuit current density and the incident photon-to-electron conversion efficiency to about 90% across the visible range. Our results demonstrate a great promise in developing high-efficiency graphene-Si solar cells in parallel to the more extensively studied carbon nanotube-Si structures.

Concepts: Electric current, Solar cell, Energy conversion, Energy conversion efficiency, Germanium, IBM


Replacement of the TiO2 layer in a traditional dye sensitized solar cell (DSC) by poly[3-(2-hydroxyethyl)-2,5-thienylene] grafted reduced graphene oxide (PHET-g-rGO) yields an overall power conversion efficiency of 3.06% with the N-719 dye, where the rGO part increases the charge mobility by reducing the backward recombination reaction in the DSC.

Concepts: Electrochemistry, Cadmium, Solar cell, Titanium dioxide, Energy conversion, Energy conversion efficiency, IBM, Solar cells


Two new D-π-A sensitizers ( and ) incorporating 5H-[1,2,5]thiadiazolo [3,4-f]isoindole-5,7(6H)-dione and 6H-pyrrolo[3,4-g]quinoxaline-6,8(7H)-dione core structures were synthesized and tested in liquid dye-sensitized solar cells (DSCs). achieved a promising power conversion efficiency (PCE) of 6.2% (AM 1.5, 100 mW cm(-2)).

Concepts: Solar cell, Titanium dioxide, Energy conversion, Energy conversion efficiency, Dye-sensitized solar cell, Thin film solar cell, IBM, Conversion of units


A mixed halide perovskite of CH3NH3PbI3-xClx is synthesized via two-step sequential solution deposition by using a mixture of PbCl2 and PbI2 as the precursor to overcome the low solubility of pure PbCl2 with easy morphology control. 11.7% power conversion efficiency is achieved for the mesoscopic cell, much higher than the cell constructed via a spin-coating process.

Concepts: Solubility, Mixture, Solar cell, Energy conversion, Energy conversion efficiency, Mixture model, IBM, Lead(II) iodide


Few-layered transition metal dichalcogenides (TMDs) are known as true two-dimensional materials, with excellent semiconducting properties and strong light-matter interaction. Thus, TMDs are attractive materials for semitransparent and flexible solar cells for use in various applications. Hoewver, despite the recent progress, the development of a scalable method to fabricate semitransparent and flexible solar cells with mono- or few-layered TMDs remains a crucial challenge. Here, we show easy and scalable fabrication of a few-layered TMD solar cell using a Schottky-type configuration to obtain a power conversion efficiency (PCE) of approximately 0.7%, which is the highest value reported with few-layered TMDs. Clear power generation was also observed for a device fabricated on a large SiO2 and flexible substrate, demonstrating that our method has high potential for scalable production. In addition, systematic investigation revealed that the PCE and external quantum efficiency (EQE) strongly depended on the type of photogenerated excitons (A, B, and C) because of different carrier dynamics. Because high solar cell performance along with excellent scalability can be achieved through the proposed process, our fabrication method will contribute to accelerating the industrial use of TMDs as semitransparent and flexible solar cells.

Concepts: Cadmium, Solar cell, Energy conversion, Energy conversion efficiency, Wafer, Diode, IBM, Flexible electronics


A colloidal quantum dot solar cell is fabricated by spray coating under ambient conditions. By developing a room temperature spray coating technique and implementing a fully automated process with near monolayer control-an approach termed as sprayLD-an electronic defect is eliminated resulting in solar cell performance and statistical distribution superior to prior batch-processed methods along with hero performance of 8.1%.

Concepts: Photoelectric effect, Quantum dot, Cadmium, Solar cell, Photovoltaics, Diode, Band gap, IBM


A nonfullerene-based polymer solar cell (PSC) which significantly outperforms fullerene-based PSCs with respect to the power-conversion efficiency is demonstrated for the first time. An efficiency >11%, which is among the top values in the PSC field, and excellent thermal stability is obtained using PBDB-T and ITIC as donor and acceptor, respectively.

Concepts: DNA, Cadmium, Solar cell, Photovoltaics, Organic solar cell, IBM


The preparation of uniform, high-crystallinity planar perovskite films with high-aspect-ratio grains over a square-inch area is demonstrated. The best power conversion efficiency (PCE) of 16.3% (stabilized output of ≈15.6%) is obtained for a planar perovskite solar cell (PSC) with 1.2 cm2 active area, and the PCE jumps to 18.3% (stabilized output of ≈17.5%) for a PSC with a 0.12 cm2 active area.

Concepts: Cadmium, Solar cell, Photovoltaics, Energy conversion, Energy conversion efficiency, IBM


Fullerene-free organic solar cells show over 11% power conversion efficiency, processed by low toxic solvents. The applied donor and acceptor in the bulk heterojunction exhibit almost the same highest occupied molecular orbital level, yet exhibit very efficient charge creation.

Concepts: Oxygen, Chemistry, Solar cell, Photovoltaics, Organic solar cell, Energy conversion, Energy conversion efficiency, IBM