Inverted OPVs with MoS2 hole transport layer deposited by spray coating

Molybdenum disulphide (MoS2) exhibits high work function and high mobility, making it a promising candidate for electronic applications. Currently, most applications require high vacuum or high reaction temperature processes to deposit MoS2. Here, we report organic photovoltaic devices made by roomtemperature spray-coating of liquid-exfoliated MoS2 suspension to form hole transport layer (HTL) on top of poly(3-hexylthiophene): phenyl-C60-butyric acid methyl ester bulk heterojunction. Such an approach is compatible with large area applications. Current-voltage data showed that fill factor of devices with MoS2 HTL is similar to the devices using poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) HTL. However, open circuit voltage and short circuit current density (J(sc)) are reduced, with the amount of J(sc) reduction depending strongly on active layer thickness. These results can be understood by the strong absorption of light by MoS2, reducing/eliminating the back reflection from the top silver electrode. The experimental results are corroborated by calculations using transfer matrix method. (C) 2017 Elsevier Ltd. All rights reserved.