Quasi-omnidirectional crystalline silicon solar cells

Crystalline silicon (c-Si) solar cells play an important role in the photovoltaic (PV) industry and make PV electricity begin to realize grid parity. Nevertheless, conventional c-Si solar cells are sensitive to angle of incidence (AOI) and have less power conversion efficiency (eta) under oblique AOI, which influences the maximization of daily/yearly power output as the sun moves with time. Although the use of sun-tracking systems is an effective way to solve this problem, it is costly. As regards increasing the daily/yearly power output with low cost, quasi-omnidirectional c-Si solar cells are good candidates and have attracted considerable interest. The eta of these solar cells is insensitive to AOI within a large range (for example, <60 degrees) due to their quasi-omnidirectional antireflection ability. In this article, we will review different antireflection mechanisms and show how to realize quasi-omnidirectional antireflection in c-Si solar cells by specific structures, especially Si nanostructures due to their superior ability in manipulating light. We will see that quasi-omnidirectional c-Si solar cells can be realized by various Si nanostructures, but most of them suffer from lower eta than conventional c-Si solar cells because of much more severe carrier recombination. Therefore, we will also present an overview of countermeasures and progress in mitigating electrical loss of quasi-omnidirectional c-Si solar cells. Finally, we will demonstrate high-performance quasi-omnidirectional c-Si, ultrathin c-Si and multicrystalline silicon solar cells realized by Si nanostructures with low aspect ratios and their advantages compared to their conventional c-Si counterparts.