Increasing the current in a white LED above specific value leads to decrease in the luminous efficacy. The efficacy of the LED under this current is appreciably higher than the conventional lightening sources. This phenomenon is known as the dark side of the white LED. It hindered the introduction of white LEDs as a commercial light source. What is the state of the art of the solid state lamps and what is their future?
The future of solid state lighting is very bright.
Right now the problem you mention is being sidestepped by including multiple LEDs in the package which are operated at lower currents where the efficiency is high. Since the price of individual LEDs is dropping and the cost of the light bulb is more dependent on the packaging and heat removal. For the short term as companies want to capture market share this appears to be a viable strategy. Beside power efficiency other issues include aesthetics, color quality and making the LED bulbs resemble the optical qualities of their incandescent ancestors.
Dear John,
Thank you very much for your contribution. You share in answering my question. This very fine from you. Your effort is very appreciated.
Could you please as an expert in leds inform us about the performance parametes of the the state of the art lightening leds.
Zekry
Hello All,
I would like to add in this discussion about organic light emitting diodes (OLEDs). In OLEDs, a very low amount of current (~50 mA) is required so it is quite beneficial in that terms. White OLEDs with nearly fluorescent lams are reported. See this link
http://www.nature.com/nature/journal/v459/n7244/abs/nature08003.html
Many industrial companies (such as OSRAM, KODAK) are going to produce solid state light sources based on OLEDs in near future.
Therefore, OLEDs have also progressed to be used as solid state lighting sources. See following links for their industrial status
http://www.osram.com/osram_com/trends-and-knowledge/oled--home/index.jsp?mkturl=oled.
Arunandan
Dear colleagues,
I would like to thank you for introducing useful information about the lightening LEDS.
From presented information i can conclude that:
- The solid state lamps are the lamps of the future because of their advantages over the conventional light sources in the form of light bulbs. The ssl are characterized by: high efficacy,electrical energy saving, compactness, robustness as they are solid,and consequently long lifetime.The main draw backs are: the relatively high cost at the present time in addition to the color appearance and color rendering.
I am very convinced that the solid state lamps will mostly displace the conventional light bulbs as the transistors as solid state devices displaced previously the electronic vacuum tubes in the fifties of the last century.
Very intensive research is running and planned to improve the performance and reduce the cost of ssl to capture their very vital advantages.When USA plans for something you will be sure of its importance. For more details see the link: http://www1.eere.energy.gov/buildings/ssl/sslbasics_ledbasics.html
Thank you
CRI of LEDs is not so significant problem any more, but the melatonin supression. Nevertheless energy efficacy gives the direction and the future in lighting are probably LEDs - as you all agreed. But then another consequence of mass use of LEDs appears - a significant influence on the supply network with the harmonic distortions.
Dear Urszula,
welcome
Yes now the LED lamps are commercialized and their effect on the supply network is real. But there are now methods to eliminate the distortion using active filters. When problems are introduced because of nature of certain loads, remedy will be found. I would like that you evaluate our developed LED lumenaire in the paper at the link:Article Careful Development Can Enhance LED Luminaire for Office Lighting
Best wishes