Comparison of concepts for inkjet-printed semi-transparent perovskite solar cells for building-integrated photovoltaics

Semi-transparent photovoltaic devices are of major interest in the steadily growing market of building-integrated photovoltaics, allowing incorporation of windows and see-through roofs that enable partial energy conversion of the incoming sunlight. Solar cells based on perovskite absorber attract increasing attention in this field of research, since they not only promise high efficiencies but also, as an evaporation- or solution-processable thin-film technology, offer new approaches to achieve semi-transparency. A deposition technique that merits closer examination in that regard is inkjet-printing. This process allows fast, material efficient and contactless material deposition in almost arbitrary shape. This work shows the progress we have achieved on the fabrication of semi-transparent inkjet-printed perovskite solar cells (PSCs). We compare three different concepts to increase the transparency of the device: i) Modulation of film thickness by inkjet-printing resolution, ii) micro-structuring by modification of the perovskite ink and iii) micro-structuring by an additional inkjet-printed transparent layer incorporated into the stack. Each concept has been demonstrated in operational PSCs, including devices with all‐inkjet‐printed absorber and charge transport layers. The varying approaches to achieve semi-transparency are presented and evaluated with regards to their transparency, its tunability, the solar cells’ aesthetics and the power conversion efficiencies (PCEs) of the devices. Reference inkjet-printed PSCs entail up to 17% PCE while devices with significantly increased transparency maintain over 60% relative PCE. Since the PSCs are based on a scalable inkjet-printing process, the results may be of major interest for future applications of semi-transparent devices in the field of building-integrated photovoltaics.