Nanocrystalline silicon (nc-Si) based p-i-n solar cells were fabricated onto various substrates using modified pulsed PECVD technique. Dark J-V characteristics of nc-Si p-i-n solar cells were found to depend strongly on the substrates and are studied at different i-layer thickness and varying the p/i interface structures. In this work, we report an almost constant diode quality factor (n = 1.2 – 1.3) up to the thickness of 3.8 μm for the devices grown on “suitably textured” ZnO substrates. The rather insensitive variation of n with i-layer thickness suggests that the dark J-V characteristics are not dominated by bulk recombination for the devices grown on textured ZnO, which prevents grain collision in the i-layer. In contrast to that, a significant change of n (1.8 – 1.3) was found while changing the p/i interface using various duration of H2 plasma treatment of nc-p surface (ST). The p/i interface structure in nc-Si p-i-n device plays the crucial role either by changing the p/i interface defects or the film structure at p/i interface determines the quality of subsequently grown nc-i layer and hence the whole device performance.