The destructive interference depends mainly on the thickness and reflective index of the coating material. Destructive interference occurs when these two waves are out of phase, canceling each other out before they escape the surface. The ARC layer creates two interfaces (one with the air and another with the silicon substrate), and hence two reflected waves are generated. A dielectric ARC with a thickness of a quarter wavelength (λ/4n) has been widely used to reduce reflections and enhance c-Si solar cell efficiency. To address this issue, numerous materials and interface designs have been suggested to minimize the reflection losses of c-Si solar cells, including proper silicon surface texturing, subwavelength structures 3, 8, plasmonic nanoparticle surfaces 9, nanostructured silicon 10, the surface passivation approach 11, 12, and application of dielectric coating as a single or multi-layer anti-reflective coating (ARC) 13, 14, 15, 16. However, around 35% of the total incident solar radiation losses are due to high optical reflection from the silicon surface of the solar cells, which does not contribute to the photovoltaic energy conversion process, reducing the efficiency of the solar cell. Reflection losses arise due to the impedance mismatch induced by the sudden change in refractive index at the interface from low refractive index air (n = 1) to high refractive index silicon (n = 4). Until recently, no experimental efficiency records have exceeded the theoretical maximum efficiency limits for c-Si solar cells, as the highest values reported to date do not exceed 90% of the maximum 7. Typically, calculations assume that both surfaces of the silicon solar cells are roughened, which optimizes optical absorption through light trapping. Theoretical calculations show that the fundamental properties of silicon limit the maximum power conversion efficiency of a c-Si solar cell to about 29% under standard operating conditions of air mass 1.5 global solar spectrum (AM1.5G) and 25 ☌ 5, 6, 7. The maximum efficiency of c-Si solar cells is determined mainly by two intrinsic recombination processes occurring within the silicon, namely radiative recombination and Auger recombination. Moreover, the fundamental properties of silicon, such as its bandgap (1.12 eV for c-Si), are nearly an ideal match to the solar spectrum, giving c-Si solar cells a dominant advantage over other semiconductor materials for solar conversion. This dominance in PV technology has been growing steadily over the last few years because of a combination of abundant materials, long-life stability, and relatively high conversion efficiency, as well as considerable cost reductions, realized via large-scale and well-developed manufacturing processes.
Over the last few decades, crystalline silicon (c-Si) solar cells have enjoyed longstanding dominance and occupied more than 90% of the global photovoltaic (PV) production market 1, 2, 3, 4. This study shows that CNx films have promising application potential as an efficient ARC for c-Si solar cells as compared to traditional ARC materials. Finally, a photoelectric conversion efficiency of 13.05% was achieved with the coated c-Si solar cell in comparison with 5.52% for the uncoated c-Si solar cell. The open circuit voltage and short circuit current density that have been achieved are 578 mV and 33.85 mAcm −2, respectively.
The minimum reflectance was 0.3% at 550 nm wavelength, and the external quantum efficiency achieved was more than 90% within the broad wavelength range. The performance of CNx film was investigated via measuring the reflectance, photoelectric conversion efficiency, and external quantum efficiency. The CNx film was synthesized by the RF magnetron sputtering technique and characterized by different chemical, structural, and optical analysis techniques. The main objective of this work is to synthesize an amorphous carbon nitride CNx thin film as a novel dual-function anti-reflection coating (ARC) for c-Si solar cells. To improve the efficiency of the solar cell, anti-reflection and self-cleaning coatings must be applied to the surface. However, due to high reflectivity and the presence of numerous types of surface contaminants, the solar cell only absorbs a limited amount of the incident solar radiation. Crystalline silicon (c-Si) solar cells have dominated the photovoltaic industry for decades.