Efficient Micrometer Thick Bifacial Perovskite Solar Cells
Nathan Rodkey, Kassio P. S. Zanoni, Manuel Piot, Chris Dreeßen, Roos Grote, Perrine Carroy, J. Alonso, Abhyuday Paliwal, D. Muñoz, Henk J. Bolink
Abstract
Abstract Perovskite solar cells have become promising candidates for thin‐film photovoltaics (PV), but many record cells suffer from losses in current (≈3–4 mA cm −2 ). This is due to the choice of superstrate configurations (i.e., glass‐side illumination) and thin absorber layers, typically on the order of ≈500 nm. Illumination through a top transparent conductive oxide electrode (substrate configuration) using LiF and Al 2 O x as anti‐reflective coatings leads to reflectance losses below 1% is demonstrated. When combined with 1 µm thick absorber layers, substrate configurated bifacial devices have power conversion efficiencies >20%, with minimized reflection losses approaching 98% of their detailed‐balance limits and higher Jsc than their monofacial counterparts. Further analysis is conducted to show there is still a significant fraction of current lost due to poor charge‐carrier extraction (e.g., resistive or low mobility contacts). This is studied by a direct comparison of photoluminescence at short‐circuit versus open‐circuit estimating a 4.5% loss in charge‐carrier collection.