SnSe₂ Quantum Dots and Chlorhexidine Acetate Suppress Synergistically Non-radiative Recombination Loss for High...

Non-radiative recombination losses limit the property of perovskite solar cells (PSCs). Here, a synergistic strategy of SnSe₂QDs doping into SnO₂ and chlorhexidine acetate (CA) coating on the surface of perovskite is proposed. The introduction of 2D SnSe₂QDs reduces the oxygen vacancy defects and increases the carrier mobility of SnO₂. The optimized SnO₂ as a buried interface obviously improves the crystallization quality of perovskite. The CA containing abundant active sites of ─NH₂/─NH─, ─C═N, CO, ─Cl groups passivate the defects on the surface and grain boundary of perovskite. The alkyl chain of CA also improves the hydrophobicity of perovskite. Moreover, the synergism of SnSe₂QDs and CA releases the residual stress and regulates the energy level arrangement at the top and bottom interface of perovskite. Benefiting from these advantages, the bulk and interface non-radiative recombination loss is greatly suppressed and thereby increases the carrier transport and extraction in devices. As a result, the best power conversion efficiency (PCE) of 23.41% for rigid PSCs and the best PCE of 21.84% for flexible PSCs are reached. The rigid PSC maintains 89% of initial efficiency after storing nitrogen for 3100 h. The flexible PSCs retain 87% of the initial PCE after 5000 bending cycles at a bending radius of 5 mm.