Enhancing Si/Organic Hybrid Solar Cells via Optimizing PEDOT:PSS Optical Properties and Anode Surface Contacts

In this paper, we investigate the absorption of organic material (poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)-PEDOT:PSS), optical properties of silver nanowires (AgNWs), and device performance enhancement of Si nanostructure/PEDOT:PSS hybrid solar cells with diluted PEDOT:PSS and AgNWs. First, silicon nanoholes (SiNHs) are well known as effective structures to reduce solar cell reflectance and enhance light harvesting. However, hole-transport organic material can also absorb light; therefore, the silicon absorption is reduced. The device current is then limited. Although PEDOT: PSS diluted through isopropanol (IPA) can reduce the thickness of PEDOT: PSS and, thus, its absorption, its adhesion to indium tin oxide (ITO) is also degraded. Therefore, here, a set of metal grids is used to replace the ITO, but its series resistance is increased due to the long path of carriers passing the thin nanostructured PEDOT:PSS morphology. We hence further added AgNWs to improve the contact between PEDOT: PSS and the metal grid. The results show that, through the dilution by IPA, the absorption of PEDOT: PSS was reduced to the value near zero, and power conversion efficiency (PCE) enhanced from 10.09% to 12.01%. With the anode of the AgNW/Ag grid and optimized PEDOT:PSS, the performance of SiNH/PEDOT:PSS hybrid solar cells reaches a PCE of 14.56%, a short-circuit current density (J(sc)) of 35.55 mA/cm(2), an open-circuit voltage (V-oc) of 0.574 V, and a fill factor of 71.37%. This paper provides a simple method to optimize Si/organic hybrid solar cells.