A combination of Al-doped ZnO and a conjugated polyelectrolyte interlayer for small molecule solution-processed solar cells with an inverted structure

Abstract

We successfully demonstrate a smart strategy to use aluminum doped ZnO (AZO) and the thiophene-based conjugated polyelectrolyte P3TMAHT as an interfacial layer in small molecule solution-processed inverted solar cells. Modification of AZO with a thin P3TMAHT layer increases the photovoltaic properties of the inverted cell as a result of reduction in the work function of the cathode with well aligned frontier orbital energy levels for efficient charge transport and reduced surface recombination. The inverted device achieved 16% performance improvement dominantly by recapturing part of the V_oc losses when going from conventional to the inverted architecture. In addition, the inverted device using the AZO/P3TMAHT interlayer shows improved device stability in air compared to conventional devices.