Organic: PbS-nanocrystal:fullerene hybrid photovoltaics

Single and multi junction hybrid devices comprising oligoacenes, PbS quantum dots (PbS-QD) and C₆₀ are demonstrated. A greatly improved performance of the PbS-QD /C₆₀ system was obtained in this work. Furthermore, a study of using acenes (pentacene, tetracene) as light absorbers and photoinduced electron donors to PbS-QD was carried out. Fabricated devices were characterized under 1 Sun simulated solar irradiation and external quantum efficiency (EQE) measurements. The initial hybrid devices demonstrated up to 0.14 % power conversion efficiency under AM1.5G illumination and up to 16 % EQE at 400 nm. The single junction (PbS-QD/C₆₀) devices demonstrated greater than 1.2 % EQE at 1100 nm while multi junctional tetracene/PbS-QD/C ₆₀) devices exhibited up to 0.2 % EQE in the infrared region (1100 nm). Ultraviolet photoelectron spectroscopy was used to measure the molecular energy levels in the system under discussion to justify the photoinduced charge transfer. This work demonstrates new device systems which can be potentially be utilized to fabricate high efficient broad band absorbing hybrid photovoltaics.