Enhanced performance of carbon-based perovskite solar cells driven by N, N′-bis-(3-(3,5-di-tert-butyl-4 hydroxyphenyl) propionyl) hexanediamine

Chemical passivation is crucial to improving the stability and power conversion efficiency (PCE) of the perovskite solar cells (PSCs). In this section we use density functional theory to investigate the major defects of uncoordinated I⁻ and Pb²⁺ on the perovskite film surface. Meanwhile, an antioxidant material, N, N′-bis-(3-(3,5-di-tert-butyl-4 hydroxyphenyl) propionyl) hexanediamine (antioxidant 1098), is intended to passivate defects in perovskite films. Theoretical studies indicate that the antioxidant 1098 bound to I⁻ and Pb²⁺ on the perovskite film surface through Lewis base-acid interactions, which is enhanced by additional hydrogen bonds (H bonds) due to the antioxidant 1098. On the other hand, the passivation effect leads to a notable reduction in trap density and an extended charge lifetime on the perovskite films' surface. The main function of antioxidant 1098 is that the N atom provides lone electron pairs to combine with Pb atom, forming coordination bonds to improve the coordination ability of Pb²⁺, and reduce the defects of perovskite films. More importantly, the antioxidant 1098 can inhibit the oxidation reaction of perovskite and effectively improve the stability of perovskite devices. Lastly, the PCE of the champion device reaches 17.03 %, and the device that is not enclosed could maintain 96 % of its original efficiency after 1200 h under atmosphere conditions (RH = 30–40 %). This study offers a method for developing the air-processed stable carbon-based perovskite solar cells (C–PSCs) by chemical passivation.