Perovskite solar cells (PSCs) have raised research interest in scientific community because their power conversion efficiency is comparable to that of traditional commercial solar cells (i.e., amorphous Si, GaAs, and CdTe). Apart from that, PSCs are lightweight, are flexible, and have low production costs. Recently, graphene has been used as a novel material for PSC applications due to its excellent optical, electrical, and mechanical properties. The hydrophobic nature of graphene surface can provide protection against air moisture from the surrounding medium, which can improve the lifetime of devices. Herein, we review recent developments in the use of graphene for PSC applications as a conductive electrode, carrier transporting material, and stabilizer material. By exploring the application of graphene in PSCs, a new class of strategies can be developed to improve the device performance and stability before it can be commercialized in the photovoltaic market in the near future.
The silicon heterojunction solar cell (SHJ) is considered the dominant state-of-the-art silicon solar cell technology due to its excellent passivation quality and high efficiency. However, SHJ's light management performance is limited by its narrow optical absorption in long-wave near-infrared (NIR) due to the front, and back tin-doped indium oxide (ITO) layer's free carrier absorption and reflection losses. Despite the light-trapping efficiency (LTE) schemes adopted by SHJ in terms of back surface texturing, the previous investigations highlighted the ITO layer as a reason for an essential long-wavelength light loss mechanism in SHJ solar cells. In this study, we propose the use of Molybdenum disulfide (MoS2) as a way of improving back-reflection in SHJ. The text presents simulations of the optical response in the backside of the SHJ applying the Monte-Carlo raytracing method with a web-based Sunsolve high-precision raytracing tool. The solar cells' electrical parameters were also resolved using the standard electrical equivalent circuit model provided by Sunsolve. The proposed structure geometry slightly improved the SHJ cell optical current density by ~0.37% (rel.), and hence efficiency (η) by about 0.4% (rel.). The SHJ cell efficiency improved by 21.68% after applying thinner back ITO of about 30 nm overlayed on ~1 nm MoS2. The efficiency improvement following the application of MoS2 is tentatively attributed to the increased NIR absorption in the silicon bulk due to the light constructive interface with the backside components, namely silver (Ag) and ITO. Study outcomes showed that improved SHJ efficiency could be further optimized by addressing front cell components, mainly front ITO and MoS2 contact engineering.