Power/Performance Bits: Dec. 23

Glimpsing pathway of sunlight to electricity
According to University of Oregon and Lund University researchers, four pulses of laser light on nanoparticle photocells in a University of Oregon spectroscopy experiment have opened a window on how captured sunlight can be converted into electricity.

The work, which the researchers expect could inspire devices with improved efficiency in solar energy conversion, was performed on photocells that used lead-sulfide quantum dots as photoactive semiconductor material.

In the process studied, each single photon, or particle of sunlight, that is absorbed potentially creates multiple packets of energy called excitons. These packets can subsequently generate multiple free electrons that generate electricity in a process known as multiple exciton generation (MEG). In most solar cells, each absorbed photon creates just one potential free electron.  

Multiple exciton generation is of interest because it can lead to solar cells that generate more electrical current and make them more efficient. This work is believed to shine new light on the little understood process of MEG in nanomaterials.

Radical energy reduction?
Researchers at UC Berkeley have reported that they’ve directly observed a long-hypothesized but elusive phenomenon called “negative capacitance,” in work that includes a unique reaction of electrical charge to applied voltage in a ferroelectric material. They believe this could open the door to a radical reduction in the power consumed by transistors and the devices containing them.

While ordinary capacitors store charge as a voltage is applied to them, this new work has revealed a paradoxical response: when the applied voltage is increased, the charge goes down.

The atomic structure of a ferroelectric material exhibits the so-called “negative capacitance” effect. If successfully built into transistors, it could drastically reduce the electricity needed to run computer processors and other transistor-dependent devices. (Source: UC Berkeley)

If successfully integrated into transistors, the researchers expect this could reduce the amount of power they consume by at least an order of magnitude, and perhaps more — leading to longer-lasting cell phone batteries, less energy-consumptive computers of all types, and, perhaps even more importantly, could extend Moore’s Law by decades.