Toward high‐efficiency stable 2D/3D perovskite solar cells by incorporating multifunctional CNT:TiO₂ additives into 3D perovskite layer

Abstract

The power conversion efficiency (PCE) of 2D/3D perovskite solar cells (PSCs) is still significantly low compared with 3D PSCs due to the poor charge transport ability of 2D perovskite thin films and a large number of defects in 3D thin films. Herein, to address these two issues, multifunctional TiO2 nanoparticles (NPs)‐modified carbon nanotubes (CNT:TiO2) additives are incorporated into 3D perovskite layer for the first time, and demonstrate three positive effects for CNT:TiO2 material application: firstly, it passivates the defect state of the 3D perovskite layer and enhances the charge mobility of the 3D layer; secondly, its interaction with the 2D film increases the conductivity of the 2D layer and produces the interface polarization electric field to promote the hole extraction. As a consequence, not only the PCE of the optimized 2D/3D PSCs with the CNT:TiO2 is greatly improved to 22.7% from 19.8% of the control PSCs, but also the stability is significantly improved.

Improved Efficiency and Stability of Perovskite Solar Cells Using the Multifunctional Additive Au Clusters

“…SSPL and TRPL measurements are conducted to research the effect of Au clusters on the carrier lifetime of perovskite films. The used excitation wavelength is 515 nm, which is the same as we reported previously. , As can be seen from Figure a, the PL peaks of both films are around 786 nm, and the PL intensity of ITO/SnO 2 -KCl@KF/CsFAMA with Au clusters doped in the CsFAMA perovskite is much lower than that of the one without Au clusters, which indicates that the photogenerated charges can be transferred more easily from the CsFAMA into the electron transport layer or hole transport layer through the continuous channel formed by perovskite crystals. Further quantitative analysis of photoinduced charge extraction and transport processes was carried out, the TRPL decays of the SnO 2 -KCl@KF/CsFAMA films with/without Au clusters were detected at 775 nm, and the results are shown in Figure b.…”

Improved performance of perovskite solar cellsviacombining Pb–Sn alloying with the passivation effect of SnI2

“…The faster the transfer and extraction of photogenerated electrons, the lower the carrier loss in SnI 2 modied devices. [36][37][38] Meanwhile, the PL peak has a slight blue-shi and the full width at half maximum (FWHM) increases aer introducing SnI 2 , which may be due to the formation of Sn-Pb alloying perovskite and the passivation effect of SnI 2 . 39 To quantify the photoinduced charge extraction and transport processes, the TRPL decay curves were obtained as shown in Fig.…”

Strategies for high‐performance perovskite solar cells from materials, film engineering to carrier dynamics and photon management

“…302,303 Very recently, multifunctional TiO 2 NPs-modified carbon nanotubes (CNT:TiO 2 ) additives were also incorporated into 3D perovskite layer by our group for the 2D/3D HPSCs with an efficiency of 22.7%, which not only passivated the defect state of the 3D perovskite layer and enhanced the charge mobility of the 3D layer, but also increased the conductivity of the 2D layer and produced the interface polarization electric field to promote the hole extraction through its interaction with the 2D film. 304 12D).…”

“…For example, our group incorporated CdS quantum dots and metal complex Cd(SCN 2 H 4 ) 2 Cl 2 into CH 3 NH 3 PbI 3 active layer through in situ synthesis to prepare bulk‐heterojunction films for HPSCs, which improved the quality of perovskite films and effectively reduce defect state density on the CH 3 NH 3 PbI 3 crystal surface, thereby decreasing the charge recombination and facilitating charge transport in the HPSCs 302,303 . Very recently, multifunctional TiO 2 NPs‐modified carbon nanotubes (CNT:TiO 2 ) additives were also incorporated into 3D perovskite layer by our group for the 2D/3D HPSCs with an efficiency of 22.7%, which not only passivated the defect state of the 3D perovskite layer and enhanced the charge mobility of the 3D layer, but also increased the conductivity of the 2D layer and produced the interface polarization electric field to promote the hole extraction through its interaction with the 2D film 304 . Jeong et al 65 developed a pseudo‐halide anion formate (HCOO − ) to suppress anion vacancy defects at the grain boundaries and the surface of the FAPbI 3 perovskite films.…”