Efficient Formamidinium-Based Planar Perovskite Solar Cells Fabricated Through a CaI₂–PbI₂ Precursor

Abstract

The performance of perovskite solar cells (PSCs) is sensitive to the quality of perovskite films. Sequential deposition enabling the controlled growth of film is promising to obtain high-quality perovskite films. However, it is challenging to fabricate formamidinium-based planar PSCs via sequential deposition, mainly due to the small penetration depth of the large size formamidinium cation into a compact PbI2 film during perovskite formation. Here, CaI2 is introduced into PbI2 precursor solution, which brings two benefits. First, the porous low-crystalline CaI2–PbI2 film results in reduced local nucleation sites and improved perovskite conversion, leading to perovskite films with high crystallinity and larger grains. Second, the residual CaI2 existing at the surface and grain boundaries of the perovskite films can passivate the detrimental crystal defects. Solar cells based on the CaI2–PbI2 precursor demonstrate high open-circuit voltage (V oc) up to 1.14 V and improved power conversion efficiency (PCE) of more than 20%, as compared to the control cells with PCEs of about 18% and V oc of 1.10 V. Moreover, the CaI2–PbI2 based devices show enhanced stability that maintains 98% of the initial PCE after 12 days under the natural environment.

High‐Performance Planar Heterojunction Perovskite Solar Cells Based on BaCl2 Additive and Power Conversion Efficiency of Over 21%

“…Consequently, the optimized perovskite film can decrease the energy level barrier at the interface with SnO 2 ; this can facilitate excellent electron transport, reduce energy loss in the process of charge separation, and contribute to the enhancement of J sc and V oc . [ 35,36 ]…”

“…Consequently, the optimized perovskite film can decrease the energy level barrier at the interface with SnO 2 ; this can facilitate excellent electron transport, reduce energy loss in the process of charge separation, and contribute to the enhancement of J sc and V oc . [35,36] The UV-vis absorption spectra of the perovskite films under different masses BaCl 2 additive were shown in Figure 4a. By spin-coating the perovskite precursor solution on the conductive substrate, the UV-vis spectra of the films were tested after heating to examine the optical band gap of the perovskite with an initial wavelength of 900 nm.…”

Facile Surface Engineering of Composite Electron Transport Layer for Highly Efficient Perovskite Solar Cells with a Fill Factor Exceeding 81%

“…At the same time, it has been pointed out that more PbI 2 is beneficial to the improvement of device performance. [ 42,43 ] The influence of the 10 mg KC‐SnO 2 on optical properties of perovskite thin films was further investigated by recording the UV–vis absorption spectra, as shown in Figure 5f. It has been shown that the absorption edge for the perovskite thin films based on reference SnO 2 and 10 mg KC‐SnO 2 ETLs appeared about 790 nm.…”

Directing the Absorption Peaks of Plasmoinc Solar Cell

“…Several structures including surface texturing [4][5][6], anti-reflection coatings [7,8], photonic crystals [9], nanogratings [10,11], and metallic nanoparticles [12][13] have been presented to enhance the absorption of plasmonic solar cells. Solar cells are generally classified into four generations [14][15][16][17][18]. By various Received:20 May, 2020, Accepted: 31 July , 2020 techniques of nanostructures, light can be concentrated in a thin absorber layer through scattering, enhanced near-field, or surface plasmon polariton phenomenon [1,2].…”