Multi-site anchoring of single-molecule for efficient and stable perovskite solar cells with lead shielding

The emergence of perovskite solar cells (PSCs) has greatly promoted the progress of photovoltaic technologies. The rapid development of PSCs has been driven by the advances in optimizing perovskite films and their adjacent interfaces. However, the polycrystalline perovskite layers in most highly efficient PSCs still contain various defects that greatly limit photovoltaic performance and stability of the devices. Herein, we introduce a multifunctional additive ethylene diamine tetra methylene phosphonic sodium (EDTMPS) with multiple anchor points into the precursor of perovskite to improve the efficiency and stability of PSCs and provide in-situ protection of lead leakage. The addition of EDTMPS acts as a crystal growth controller and passivation agent for perovskite films, thereby slowing down the crystallization rate of the film and obtaining high-quality perovskite films. Our study also provides an insight into how the modifier modulate the interfacial energy level arrangement as well as affect transfer of charge carriers and their recombination under photoinduced excitation. As a result, the power conversion efficiency (PCE) of single subcell with a working area of 0.255 cm2 increases significantly from 20.03% to 23.37%. Moreover, we obtained a PCE of 19.16% for the 25 cm2 module. Importantly, the unencapsulated EDTMP-modified PSCs exhibit better operational and thermal stability, as well as in-situ absorption of leaked lead ions.