Fabrication of highly efficient hybrid solar cells based on SiNWs/PEDOT:PSS

Abstract

In recent years, Si/PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)) hybrid solar cells have been getting increasing attention due to its many advantages such as the simple fabrication process, low temperature process and low-cost compared to conventional silicon solar cells which require high temperature process such as dopant diffusion. For enhancing the efficiency in hybrid solar cells, silicon nanowires have been introduced because of higher light absorption and an easier carrier transport. Therefore, more carriers can be generated and collected, resulting in a higher short-circuit current density (Jsc). For fabricating silicon nanowires, we have adopted the metal-assisted chemical etching (MacEtch) method based on the self-assembled ITO nano-patterning method which can control nano-dots dimension. Although this method is less well-known than electron beam lithography, nanosphere lithography and nano-imprint lithography, it is an inexpensive and simple process. In this study, we have demonstrated inorganic/organic hybrid solar cells consisting of a silicon substrate based on the nano-structure fabricated by metal-assisted chemical etching (MacEtch) using self-assembled ITO nano-dots and PEDOT:PSS. Furthermore, various morphology silicon nanowires were achieved by changing etching solution and metal catalyst thickness. Generally, reflectance of planar silicon substrate shows average 35 % in visible-NIR regions from 300 to 1200 nm, whereas that of various morphology nano-structured silicon substrate shows below 5 %. Furthermore, we have demonstrated highly efficient SiNWs/PEDOT:PSS hybrid solar cells, which were fabricated using a simple fabrication process, have demonstrated an excellent short circuit current density (Jsc) of 38.75 mA/cm2 which is similar to the theoretical Jsc value of 39.0 mA/cm2. Also, from the current density-voltage measurement of the hybrid solar cells under AM 1.5, the fill factor (FF), open circuit voltage (Voc) and power conversion efficiency (PCE) were 58.14 %, 0.570 V and 12.84 %, respectively.