Molecular Passivation of MoO₃: Band Alignment and Protection of Charge Transport Layers in Vacuum-Deposited Perovskite Solar Cells

Abstract

Vacuum deposition of perovskite solar cells can achieve efficiencies rivaling solution-based methods and allows for more complex device stacks. MoO3 has been used to enhance carrier extraction to the transparent bottom electrode in a p-i-n configuration; here, we show that by inserting an molecular interlayer with a lone pair nitrogen atom and low ionization potential, it can also be used on the top of a perovskite absorber in a n-i-p configuration. This strategy enables the first vacuum-deposited perovskite solar cells with metal oxides as charge transporting layers for both electrons and holes, leading to power conversion efficiency >19%.

Perovskite Solar Cells: Stable under Space Conditions

“…The typical performance of the solar cells using the films is similar as previously reported, [ 21 ] and the current density ( J ) versus voltage ( V ) curves when illuminated with 1 sun of AM1.5 spectrum are shown in Figure 1d. The key performance parameters derived from the J – V curve are as follows: J sc of 20.6 mA cm −2 , V oc of 1.16 V, and FF of 78% leading to a PCE of 18.6%.…”

Robust Inorganic Hole Transport Materials for Organic and Perovskite Solar Cells: Insights into Materials Electronic Properties and Device Performance

“…The inferior performance can be overcome using interlayers that improve energy‐level alignment and also avoid interfacial degradation. Pérez‐del‐Rey et al [ 219 ] showed that a thin (1–2 nm) interlayer of 2,2′,2″‐(1,3,5‐Benzinetriyl)‐tris(1‐phenyl‐1‐H‐benzimidazole, TPBi, results in efficient charge extraction and a PCE exceeding 19%. The insertion of the TPBi interlayer also inhibits chemical reaction at the MoO 3 /perovskite interface.…”

Efficient Vacuum Deposited P-I-N Perovskite Solar Cells by Front Contact Optimization

“…For this study we used the following device configuration (Figure 1): ITO/MoO 3 (5 nm)/TaTm (10 nm)/MAPI (600 nm)/C 60 (25 nm)/BCP (8 nm)/Ag (in which C 60 is fullerene; BCP is bathocuproine and MAPI is methylammonium lead iodide). TaTm and C 60 are intrinsic organic materials for charge selection, and MoO 3 and BCP are p-and n-contacts for efficient extraction of the photogenerated holes and electrons, respectively (Pérez-del-Rey et al, 2019;Zanoni et al, 2019). All the layers in the device, including the MAPI perovskite film, were deposited by vacuum-assisted thermal evaporation, as described in the experimental section in the Supporting Information.…”

“…As Kelvin Probe is a surface sensitive technique, we could not extract meaningful information for the MoO 3 films coated with TaTm. In that case, the loss of oxygen upon annealing might be attenuated by the physical barrier of TaTm itself, leading to a better ohmic contact within the MoO 3 /TaTm interface (Pérez-del-Rey et al, 2019). Additionally, considering the high work function of MoO 3 , hole transfer from the TaTm to MoO 3 is likely to occur (Xu et al, 2016), resulting in interfacial doping of TaTm and hence beneficial charge extraction.…”