Tiny Crystals Promise Big Benefits for Solar Technologies

From Los Alamos National Laboratory press release, Januaray 4, 2006:

Los Alamos National Laboratory scientists have discovered that a phenomenon called carrier multiplication, in which semiconductor nanocrystals respond to photons by producing multiple electrons, is applicable to a broader array of materials that previously thought. The discovery increases the potential for the use of nanoscrystals as solar cell materials to produce higher electrical outputs than current solar cells.

In papers published recently in the journals Nature Physics and Applied Physics Letters, the scientists demonstrate that carrier multiplication is not unique to lead selenide nanocrystals, but also occurs with very high efficiency in nanocrystals of other compositions, such as cadmium selenide. In addition, these new results shed light on the mechanism for carrier multiplication, which likely occurs via the instantaneous photoexcitation of multiple electrons.

The Los Alamos findings point toward practical photovoltaic technologies that may utilize such traditional solar cell materials as cadmium telluride, which is very similar to cadmium selenide.

A very early stage research finding that could have significant impact in future generation solar cells.

Technorati tags: solar power, PV solar, energy, technology

Comments

[G Eddy]

Are there no rough estimates of relative efficiency for this technology?

[Jim from The Energy Blog]

The development of this technology is in much too early a stage of developement to enable any projections on efficiency. At this point it is a technology that has such a strong potential to increase the efficiency of solar cells that further research is justified.

[NoNam]

Research on double emission of electrons via photons has been going on for many years. The theoretical work was done in Germany at the Max Plank Labs about 7 years ago (I think). Theoritical maximum efficiency is about 65 percent, versus current single emmisions of about 35 percent. The best quality (Spectrolab) single emmission silicon does ~ 32 percent under its best operating mode (which is multiple focus suns).
This real efficiency is about 90% of the predicted theoritical. If a similiar ratio can be expected then we could see real world efficeincies of perhaps 59 percent. So a little less then double. There has been many (perhaps five) articles on "in the lab" double emmision samples having been developed, and tested in the last few years. So it works in the lab, the effort now is cost of materials/manufacturing, trying various ways to understand and tweak performance, and long term testing of performance. This could take many many years, but at least there seems a viable path to next genaration solar. Please use google to verify and fill in exact information...I did not have time.

[Jim from The Energy Blog]

NoNam--1) I beleive that previous work on this phenomena was on lead selenide and that the recent discovery was that it was observed in cadmium selenide which is similar to materials used in solar cells 2)The spectrolab solar cells are double or triple junction solar cells which is a different method of construction than the carrier multiplication penonomena described by the Los Alamos researchers.