Pulsed Laser Ablation Based Synthesis of PbS‐Quantum Dots‐Decorated One‐Dimensional Nanostructures and Their Direct Integration into Highly Efficient Nanohybrid Heterojunction‐Based Solar Cells

The pulsed laser deposition (PLD) technique is used for the direct fabrication of nanohybrid heterojunctions (NH‐HJs) solar cells exhibiting high PCE and excellent stability in air without any encapsulation and/or resorting to any surface treatment, ligand engineering and/or post‐synthesis processing. The NH‐HJs are achieved through the PLD‐based decoration of hydrothermally‐grown one‐dimensional TiO₂ nanorods (TiO₂‐NRs) by PbS quantum dots (PbS‐QDs). By optimizing both the amount of PbS‐QDs (via the number of laser ablation pulses) and the length of the TiO₂‐NRs, it is possible to achieve optimal NH‐HJs based PV devices with high power conversion efficiency (PCE) of 4.85%. This high PCE is found to occur for an optimal length of the NRs (≈290 nm) which coincides with the average penetration depth of PbS‐QDs into the porous TiO₂‐NRs matrix, leading thereby to the formation of the largest extent of NH‐HJs. Most importantly, the PCE of these novel devices is found to be fairly stable for several months under ambient air. The addition of single‐wall carbon nanotubes (SWCNTs) onto the TiO₂‐NRs prior to their decoration by PbS‐QDs is shown to further enhance their PCE to a value as high as 5.3%, because of additional light absorption and improved charge collection ensured by SWCNTs.