On the front and back side quantum efficiency differences in semi-transparent organic solar cells and photodiodes

B. Bouthinon (1) , R. Clerc (2) , J. Verilhac (1) , B. Racine (3) , J. de Girolamo (1) , S. Jacob (1) , P. Lienhard (1) , J. Joimel (4) , O. Dhez (4) , A. Revaux (1)

1 CEA/DRT/LITEN
2 LHC - Laboratoire Hubert Curien
3 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information
4 ISORG

The External Quantum Efficiency (EQE) of semi-transparent Bulk Hetero-Junction (BHJ) organic photodiodes processed in air shows significant differences when measured from the front or back side contacts. This difference was found significantly reduced when decreasing the active layer thickness or by applying a negative bias. This work brings new elements to help understanding this effect, providing a large set of experiments featuring different applied voltages, active layers, process conditions and electron and hole layers. By the mean of detailed electrical simulations, all these measurements have been found consistent with the mechanisms of irreversible photo-oxidation, modeled as deep trap states (and not as p type doping). The EQE measurement from front and back side is thus a simple and efficient way of monitoring the presence and amplitude of oxygen contamination in BHJ organic solar cells and photodiodes.

Domaines: Micro et nanotechnologies/Microélectronique

B. Bouthinon, R. Clerc, J. Verilhac, B. Racine, J. de Girolamo, et al.. On the front and back side quantum efficiency differences in semi-transparent organic solar cells and photodiodes. Journal of Applied Physics, 2018, 123, pp.125501. ⟨10.1063/1.5017030⟩. ⟨hal-01741227⟩