High-Efficiency Aqueous-Processed Hybrid Solar Cells with an Enormous Herschel Infrared Contribution

Aqueous-processed solar cells have evolved into a new generation of promising and renewable energy materials due to their excellent optical, electrical, and low-cost properties. In this work, Cd0.75Hg0.25Te colloid quantum dots (CQDs) were incorporated into a water-soluble conjugated polymer with broad absorption and high charge-carrier-mobility (5 x 10(-4) cm(2) V-1 s(-1)) to obtain a composite with an absorption spectrum ranging from 300 to 1200 nm. The matched energy level between polymer and CQDs ensured the effective electron transfer, while the interpenetrating network structure formed via heat treatment guaranteed the quick electron transport. Moreover, the formation process of the interpenetrating network was systematically monitored by using AFM and TEM instruments and further confirmed through the measurement of charge-carrier-mobility of the active layers. In combination with the surface modification of a single Cd0.75Hg0.25Te layer, this aqueous-processed solar cell showed excellent photovoltaic response and the power conversion efficiency (PCE) reached 2.7% under AM 1.5 G illumination (100 mW cm(-2)). Especially, the contribution of the Herschel infrared region (780-1100 nm) to the photocurrent was as high as 15.04%. This device showed the highest PCE among organic-inorganic hybrid solar cells (HSCs) based on CdxHg1-xTe CQDs and the highest near infrared (NIR) contribution among aqueous-processed HSCs, indicating the enormous potential of taking advantage of NIR energy in a solar spectrum and a promising application in solar cells especially used in cloudy weather.