The efficiency of photoactive devices; devices that change photon energy to electrical/chemical energy, is affected by recombination of excited electrons and holes across, the interface, surface, depletion region, in the bulk and etc. thus, to enhance the measured current and voltage of the devices controlling and vanishing the recombination rate across the device is important. Therefore, can we synthesize photoactive materials with almost zero recombination rate? Just I am wondering why and why not?
Zero recombination rate would mean infinite lifetime and this would mean that radiative, thermal, defect and Auger recombination channels have been turned off, and this would mean a material at zero absolute with no defects and no doping or intrinsic free carriers. Unfortunately, if you want an absorbing material you, at least, you can not shut down the radiative recombination just because of the microscopic reversibility. Even if you have a non-defective, non-doped material at zero absolute.
Zero recombination rate would mean infinite lifetime and this would mean that radiative, thermal, defect and Auger recombination channels have been turned off, and this would mean a material at zero absolute with no defects and no doping or intrinsic free carriers. Unfortunately, if you want an absorbing material you, at least, you can not shut down the radiative recombination just because of the microscopic reversibility. Even if you have a non-defective, non-doped material at zero absolute.
Practically you can`t, i suppose. There are surface states always on the device due to incomplete bonding. The diffusion length of the holes can be improved by nanostructuring your deivce. You might use a suitable co-catalyst too. Another way to improve your device may be to optimize its crystal growth such that the grains are in a direction which offer as low as possible resistance for the electrons to the collecting end of your device.
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