Top-Down Approach Using Laser Ablation to Achieve High-Performance Semitransparent Perovskite Solar Cells

Semitransparent perovskite solar cells (ST-PSCs) act as promising candidates for building-integrated photovoltaics (BIPVs) as windows and facades. An optimum balance between the power conversion efficiency and transparency in the visible range is required to satisfy these requirements. Amongst many ways to increase the transmittance of halide perovskite thin films, decreasing the absorber thickness by spin coating with the diluted solution is the most common way. However, these ultrathin films are discontinuous and have often pin-holes due to low concentrations of precursor ink. Thus, achieving a uniform and continuous ultrathin film with reliable scalability is of pressing need.<br/>Here, we employ a top-down approach where a pulsed UV laser is used to etch a thick pre-crystallized film till the desired transparency is achieved without any structural damage. A regressive decrease in the perovskite film thickness from ~500 nm up to ~100 nm is achieved by controlling the laser fluence and exposure time. To obtain an average visible transmittance (AVT) of &gt;22%, the perovskite film is laser ablated to ~ 250 nm. The developed semitransparent devices without any additives have shown a high PCE of &gt; 14%. Additionally, a remarkable PCE of &gt;11 % is achieved for a ~ 100 nm thick perovskite solar cell with ~ 30 % AVT. The results highlight an innovative fabrication method of laser thinning together with patterning to improve high-efficiency semitransparent PSCs while maintaining their transparency.