LEDs with 660 nm are the kings of efficiency
The deep red light colour at 660 nm has a physical advantage in terms of efficiency. The Unit of measurement PAR is in fact based on the counting of Photons in the range 400 - 700 nm.
Longer-wave red light is not as energetic as blue or even UV radiation. This means that less energy is needed to emit a red photon.
For this reason in particular - and because light in the red spectrum plays an important role in the flowering phase and photomorphogetic effects - red light is the preferred light for plant lighting.
Comparison of the efficiency of current 660 nm LEDs with the GH CSSRM4.24
Many LED semiconductor manufacturers provide data on the efficiency of red LEDs. The photosynthetic photon efficiency (PPE) is given in µmol/J and describes how many photons are emitted in the range of 400 - 700 nm per applied energy.
In the current comparison, Osram is at the top with the GH CSSRM4.24 (as of October 2020).
Oslon Square LED - 2 mm² chip for best energy yield
In the Oslon Square series, Osram is using larger LED chips than usual to achieve the impressive performance figures. The Oslon Square Hyper Red LED has been available with a 2 mm² chip ("Die") since the end of 2017. The third generation since the GH CSSRM4.24 now has a power output of over 75 %.
LED plant lamps with over 3.0 µmol/J possible
Thanks to this development, system efficiencies above 3.0 µmol/J are no longer a pipe dream. The system efficiency also takes into account driver and optical losses. Commercial LED grow lamps of well-known manufacturers are recently offered with very high efficiencies of about 2.7-2.8 µmol/J.
Crescience offers with the APEXengine 660 Mk II an easy to handle LED module with Osram GH CSSRM4.24. In combination with FLUXengine and modern Mean Well drivers plant lamps with system efficiencies above 3.0 µmol/J can be constructed.