Role of Continuous Spray Pyrolyzed synthesized MoO3 nanorods in PEDOT: PSS matrix by electric field assisted spray deposition for organic photovoltaics

Organic-inorganic hybrid solution composing of Continuous Spray Pyrolyzed (CoSP) synthesized molybdenum trioxide (MoO3) nanorods in poly(3,4-ethylene dioxy thiophene): poly(styrenesulfonate) (PEDOT:PSS) were developed to form an effective interconnecting layer for use as a hybrid hole transport layer (HTL) in organic solar cells (OSCs). Compared to that of pristine PEDOT:PSS based OSCs, the PEDOT:PSS-MoO3 based OSC demonstrates a noticeable advancement in power conversion efficiency (PCE), current density, and fill factor due to enhanced the wettability and conductivity of the composite HTL for efficient hole injection. The effect of the applied DC voltage (500 V and 1000 V) to the nozzle during the spray deposition of hybrid PEDOT:PSS-MoO3 HTL on efficient operation of the OSCs was systematically investigated. The surface roughness, compact morphology and hence the electrical conductivity of hybrid HTL are significantly influenced by the applied DC voltages during deposition of film. It is attributed to coulombic fission for better atomization of spray and generating ultrafine homogeneous droplets in corona cone, which fabricate a uniform film over a larger area. Moreover, rise in the work function was also noticed possibly due to the nanostructure formation due to MoO3 nanorods. The use of 500 V and 1000 V during fabrication of the PEDOT:PSS-MoO3 HTL resulted in the ambient condition optimized PTB7:PC71BM based OSCs reaching highest PCE of 4.68% and 5.11%, respectively. This is due to superior interface connection between hybrid HTL and photoactive layer leading to improved charge collection efficiency.