Highly efficient and stable solar cells with hybrid of nanostructures and bulk heterojunction organic semiconductors

The research in organic solar cells (OSCs) have attracted much attention in the last two decades due to their light weight, low manufacturing cost, and flexibility compared to inorganic solar cells (ISCs). However, the OSCs have not reached the commercial market yet due to their low power conversion efficiency (PCE) and low stability in comparison to ISCs. In this research, the primary focus will be to improve the PCE of bulk-heterojunction (BHJ) OSCs, which have become a promising structure with high PCE. The operation of BHJ OSCs depends on the following four main processes: (1) photon absorption and exciton generation, (2) exciton diffusion and dissociation, (3) charge transport and (4) collection of photogenerated dissociated charge carriers at their respective electrodes. The objective of this project is to develop methods and understanding for improving the efficiency of all four processes. The nanostructures like the quantum dots improve the photon absorption and the nanowires act as charge transport pathways and improve the charge transport to the respective electrodes. The moth-eye nano-structures act as effective antireflection (AR) coating to reduce the reflection losses from the surface of an OSC. Hence, integration of these nanostructures into the BHJ OSCs to improve their PCE will be thoroughly studied. The problem of stability in OSCs will be studied by analysing the factors responsible for the degradation of the organic active layer in BHJ OSCs.