Highly Efficient Semitransparent Solar Cells with Selective Absorption and Tandem Architecture.

Semitransparent (ST) photovoltaics (PVs) with selective absorption in the UV or/and near-infrared (NIR) range(s) and reduced energy losses, are critical for high-efficiency solar-window applications. Here, a high-performance tandem ST-PV with selected absorption in the desirable regions of the solar spectrum is demonstrated. An ultralarge-bandgap perovskite film (FAPbBr2.43 Cl0.57 , Eg ≈ 2.36 eV) is first developed to fulfil efficient selective absorption in the UV region. After optimization, the corresponding ST single junction (SJ) PV exhibits an averaged transmittance (AVT) of ≈68% and an efficiency of ≈7.5%. By sequentially reducing the visible absorbing component in a low-bandgap organic bulk-heterojunction layer, an ST-PV with selective absorption in the NIR is achieved with a power conversion efficiency (PCE) of 5.9% and a high AVT of 62%. The energy loss associated with the SJ ST-PVs is further reduced with a tandem architecture, which affords a high PCE of 10.7%, an AVT of 52.91%, and a light utilization efficiency up to 5.66%. These results represent the best balance of AVT and PCE among all ST-PVs reported so far, and this design should pave the road for solar windows of high performance.