Enhancing blue photoresponse in CdTe photovoltaics by luminescent down-shifting using semiconductor quantum dot/PMMA films

Commercially available semiconductor quantum dots have been encapsulated within a poly(methyl, methacrylate) polymer matrix to form a luminescent down-shifting layer. The films were deposited, via doctor blading on thin film CdTe structures. This paper demonstrates an average increase of 16% in the conversion of photons with energies greater than the window layer band gap (>2.7 eV), which would normally not produce photocurrent due to the filtering effect of the window layer. The films have been characterised using surface mapping laser beam induced current measurements (LBIC) and external quantum efficiency (EQE). While these initial results show an overall decrease in the current output from the device, the possible loss mechanisms are explored and discussed.