Suppressing Shallow Defect of Printable Mesoscopic Perovskite Solar Cells with a N719@TiO<sub>2</sub> Inorganic–Organic Core–Shell Structured Additive
Liang Xu, Yiming Li, Jiangjian Shi, Neil Robertson, Wenjun Wu, Qingbo Meng, He Tian
Abstract
Shallow defects are one of the energy states that trap photoexcited electrons leading to charge recombination and limit the increase in the photocurrent of perovskite solar cells (PSCs). Due to the large perovskite thickness and uncontrollable crystallization processes, suppressing shallow defects, especially methylamine (MA) vacancies, has become a key challenge for fully printable PSCs. Herein, nano‐TiO 2 is unprecedentedly used to load the commercial dye N719, forming N719@TiO 2 nanoparticles, which crucially improves the passivation effect of MA vacancies on the surface of perovskite and charge extraction, by the unbounded carboxyl group of N719 as a shell on the surface of TiO 2 . Meanwhile, the core TiO 2 serves as a centre to bind the dyes, assisting the perovskite crystallization and enhancing the passivation effect. It is found that the charge extraction increases to 1.8007 × 10 −9 C for the devices based on N719@TiO 2 from 1.5507 × 10 −9 C for the control group. Simultaneously, the short‐circuit current density ( J sc ) is significantly enhanced to 23.58 mA cm −2 in the device containing N719@TiO 2 over that of the control device (21.95 mA cm −2 ). This opens up a novel pathway to reduce shallow defects in PSCs via organic passivator with carboxyl anchoring group loaded on n‐type semiconductors (nano‐TiO 2 ).