Perhaps you should look at use of integrating sphere:

https://www.thorlabs.com/navigation.cfm?guide_id=2123#:~:text=Integrating%20spheres%20are%20optical%20components,sizes%20with%20a%20single%20port.

https://www.hamamatsu.com/resources/pdf/sys/SSMS0018E_C9920-12.pdf

Nikolay Pavlov I doubt using integrating sphere in finding out EQE for LED. To my understanding, one can use integrating sphere in finding out Quantum yield of a photo sensitive solid material or solution in a cuvette. Correct me if I am wrong

Manasa Perikala I believe that integrating sphere can be used for finding out EQE for LED; It traps the light emitted by the device and also is helpful for providing the absorption correction I believe . Although some modification is required to be made to the sample holders to accommodate the connection with an external circuit.

If the thin film LEDs are very small dimensions comparing with the size of an integrating sphere, you can certainly use it to measure all emitted photons from all directions. If the thin film LEDs have large 2D dimension, you could use a special integration sphere which your LEDs are not put in the centre instead of closing the edge. There are commercially available for different types of integrating spheres you can easily find from a company who deal with optical components.

Hello. 1. I support the link Nikolay Pavlov (R&D) for installation / equipment.

2. Look through "good" sources / books / tutorials, comments and pictures of thin-film planar LEDs: a) M.Sze - Ph. Sem. Dev., Part LEDs...; b) Bearg A., Dean P. - LEDs; ets ...

3. In my dissertation work, p. 3.3 (attachment 1), there is a theoretical and practical example of calculating a model of a micropower thin-film planar HR LED, the values ​​of the internal and external quantum efficiency in the case of surface radiation extraction (SRE) in one direction. If you output in two directions, the efficiency will be almost twice as much (attachment 2).

I wish you success in your researches. Nick Proskurin, Ph.D.