A Multifunctional Dye Molecule as the Interfacial Layer for Perovskite Solar Cells

Abstract

In perovskite solar cells (PSCs), defects in the interface and mismatched energy levels can damage the device performance. Improving the interface quality is an effective way to achieve efficient and stable PSCs. In this work, a multifunctional dye molecule, named ThPCyAc, was designed and synthesized to be introduced in the perovskite/HTM interface. On one hand, various functional groups on the acceptor unit can act as Lewis base to reduce defect density and suppress nonradiative combinations. On the other hand, the stepwise energy-level alignment caused by ThPCyAc decreases the accumulation of interface carriers for facilitating charge extraction and transmission. Therefore, based on the ThPCyAc molecule, the devices exhibit elevated open-circuit voltage and fill factor, resulting in the best power conversion efficiency (PCE) of 23.16%, outperforming the control sample lacking the interface layer (PCE = 21.49%). Excitingly, when attempting to apply it as a self-assembled layer in inverted devices, ThPCyAc still exhibits attractive behavior. It is worth noting that these results indicate that dye molecules have great potential in developing multifunctional interface materials to obtain higher-performance PSCs.

Chemical nanoimaging of octylphosphonic acid molecular additives on hybrid organic–inorganic perovskite films

“…The positions of the FTIR peaks show slight differences from those reported in previous studies, primarily due to the hydrogen bonding and coordination interactions between OPA and the perovskite, as well as differences in the chemical stoichiometry of the perovskite components. 24–26…”

In Situ Buried Interface Engineering towards Printable Pb–Sn Perovskite Solar Cells

“…As the efficiency of single-junction PSCs is getting closer to the Shockley–Queisser radiative limit, low-bandgap (1.2–1.4 eV) lead (Pb)–tin (Sn) perovskites are gaining significant research interest due to their all-perovskite tandem application. − A breakthrough work by Hu et al pushed the Pb–Sn perovskite (Cs 0.1 FA 0.6 MA 0.3 Sn 0.5 Pb 0.5 I 3 ) solar cell efficiency to 23.6% by incorporating a glycinium hydrochloride molecule as an additive in the perovskite precursor solution . Recent advances in suppressing Sn oxidation and crystallization regulation improved the Pb–Sn perovskite (FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 I 3 ) material quality, enabling the highest single junction and all-perovskite tandem efficiency of 23.8 and 30.1%, respectively. , Besides the bulk material quality optimization, such as suppressing detrimental Sn oxidation and crystallization modulation, the perovskite-charge transport layer (CTL) interface optimization received little attention, although it is of equal importance to realize efficient PSCs, due to the direct contact between these interfacial layers and the perovskites. − …”