14.58% Efficiency Semi‐Transparent Quasi‐Layered Polymer Solar Cells by Incorporating Trace High Hole Mobility and Crystallinity Material

ABSTRACT A series of opaque and semi‐transparent quasi‐layered polymer solar cells (QL‐PSCs) was constructed by a sequential spin‐coating method, with D18 featuring a wide optical bandgap and narrow absorption range as donor and BTP‐eC9 having self‐dissociation characteristics as acceptor. The material C8‐BTBT with high hole mobility and crystallinity is deliberately added into BTP‐eC9 layers to improve hole transport in BTP‐eC9 layers. The power conversion efficiency (PCE) of opaque QL‐PSCs is enhanced from 18.20% to 18.90% by adding 0.03 wt.% C8‐BTBT into BTP‐eC9 layers, benefiting from the enhanced short‐circuit current density ( J SC ) of 28.30 mA cm −2 and fill factor (FF) of 75.69%. The semi‐transparent QL‐PSCs were optimized by adjusting the D18 layer thickness and employing Au (1nm)/Ag (10 nm) as electrode, light‐utilization‐efficiency (LUE) of 3.96% of optimal semi‐transparent QL‐PSCs can be achieved with a PCE of 14.58% and an average visible transmittance (AVT) of 27.19%. This work indicates that the quasi‐layered (QL) strategy accompanied with trace high hole mobility and crystallinity material may provide great potential in achieving high efficient semi‐transparent QL‐PSCs.