The poly-Si IBC topology is one of the most promising silicon solar cell designs and has already achieved >26% efficiency. In this work we optimise the front surface field (FSF) and apply rear hydrogenation to the poly-Si IBC structure developed by the TU Delft PVMD group. An investigation is also made of a PECVD tunnel oxide as a replacement for NAOS oxide currently used. The PECVD method allows greater control of the layer thickness and stoichiometry, as well as the ability to grow and cap the oxide layer without breaking vacuum. This process also leads to the development of poly-SiOx passivating contacts, which exhibit lower parasitic absorption as compared with their poly-Si counterpart. The optimised PECVD oxide is implemented into FBC solar cells. In the optimisation of the FSF the best performance came from the a-Si:H/SiNx:H stack using thicknesses of 18 and 75 nm respectively. It achieved an iVoc of 731 mV and a J0 of 4 fAcm-2 on undoped textured samples. This was owing to the high hydrogen content of the materials, but had the disadvantage of parasitic absorption from the a-Si:H layer. The stack was tested against different FSF doping levels and with varying thickness to reduce the parasitic absorption. The best performance remained on the undoped (No FSF) case with 18 nm a-Si, achieving 731 mV and 13.5 fAcm-2. The selected a-Si thickness for implementation into IBCs was 9 nm. This was estimated to provide lower parasitic absorption whilst still achieving high passivation. A peak value of 722 mV was obtained for No FSF case. A study of rear hydrogenation options revealed the a-Si:H/SiNx:H layer provided the best results. The layer thicknesses were 6 and 75 nm respectively. This led to an overall passivation of 725 and 709 mV on poly-Si IBC BSF and emitter symmetrical samples. This was due to the high hydrogen content in the layers raising the passivation quality of the poly-Si passivating contacts on the c-Si interface. The implementation into IBCs was unsuccessful owing to shunting of emitter and BSF regions. The SiNx layer was too thin to withstand the post-metalisation annealing and both poly-Si regions were contacted. Peak values of 7.22% efficiency and 600 mV Voc were obtained. In the investigation of the PECVD tunnel oxide measurements different layer thicknesses were made. After a 3 minute reaction time of c-Si in N2O plasma a thickness of 1.22 nm was achieved. Growth saturated after 21 minutes at a thickness of 1.98 nm. Implementation in flat n-poly-SiOx passivating contacts showed that the oxide with 1.97 nm thickness, oxide 18, obtained the best result of 723 mV. On flat p-poly-SiOx passivating contacts the 1.85 nm oxide, oxide 12, achieved the best result of 668 mV. On textured n-poly-SiOx passivating contacts oxide 18 again performed best, with 710 mV. As the p-poly-SiOx was limiting, oxide 12 was selected for implementation into FBC cells. The implementation into FBC cells revealed that the oxide layer had a very high contact resistance value that limited performance. The best Voc of 517 mV came with an FF of 89%. A TLM measurement showed that for oxide 12 contact resistance was 3.71 kOhm-cm2. This was therefore restricting the flow of current within the cell.