Vacuum-Deposited 2D/3D Perovskite Heterojunctions

Abstract

Low-dimensional (quasi-) 2D perovskites are being extensively studied in order to enhance the stability and the open-circuit voltage of perovskite solar cells. Up to no, thin 2D perovskite layers on the surface and/or at the grain boundaries of 3D perovskite have been deposited solely by solution processing, leading to unavoidable intermixing between the two phases. In this work, we report the fabrication of 2D/3D/2D perovskite heterostructures by dual source vacuum deposition, with the aim of studying the interaction between the 3D and 2D phases as well as the charge transport properties of 2D perovskites in neat 2D/3D interfaces. Unlike what normally observed in solution-processed 3D/2D systems, we found a reduced charge transport with no direct evidence of surface passivation. This is likely due to a non-favorable orientation of the 2D perovskite with respect to the MAPI and to the formation of 2D phases with very low dimensionality (virtually pure 2D).

The Future of Perovskite Photovoltaics—Thermal Evaporation or Solution Processing?

“…reported on the formation of 3D/2D and 2D/3D/2D structures by dual‐source thermal evaporation. [ 96 ] Interestingly, and unlike similar heterostructures formed by solution‐processing, in both these examples the incorporation of the 2D perovskite did not lead to an improvement in device performance.…”

3D/2D Bilayerd Perovskite Solar Cells with an Enhanced Stability and Performance

“…Similarly, 3D and 2D perovskite layers can be independently deposited by using a thermal vacuum evaporator. Bolink et al carried out the whole vapor disposition process in a thermal evaporator, where the deposition rate and the expected deposition thickness of each source were closely monitored by quartz crystal microbalance, adjusting the temperature for sublimation [ 47 ]. The 3D bulk film was obtained by the coevaporation of PbI 2 and MAI.…”

“…The 2D capping layer was sequentially deposited on top of MAPbI 3 by another coevaporation process of PbI 2 and PEAI, which resulted in the 3D/2D bilayered structure. Thanks to the benefit of the vacuum process, a more complicated architecture composed of 2D/3D/2D was further enabled by the evaporator, leading to a neat interface between 2D and 3D layers [ 47 ].…”

Intermediate‐Adduct‐Assisted Growth of Stable CsPbI2Br Inorganic Perovskite Films for High‐Efficiency Semitransparent Solar Cells

“…Among light‐absorbers for solar cells, perovskite stands out due to its direct and tunable bandgap to absorb enough photons, [ 15–19 ] and the PCE of perovskite solar cell (PSC) has increased from 3.8% to 25.2%. [ 20–24 ] At present, methylammonium lead iodine (MAPbI 3 ) with a bandgap of 1.6 eV is widely applied in ST‐PSC, [ 25–27 ] however, its thickness must be greatly reduced for achieving enough AVT (>20%) and the J sc is also reduced accordingly. [ 28 ] In addition, it is difficult for MAPbI 3 to obtain a high V oc exceeding 1.2 V. Consequently, most reported PCEs of ST‐PSCs are below 12% when the AVT is higher than 20%.…”