Compositional and Interfacial Engineering Yield High-Performance and Stable p-i-n Perovskite Solar Cells and Mini-Modules

Abstract

Through the optimization of the perovskite precursor composition and interfaces to selective contacts, we achieved a p-i-n-type perovskite solar cell (PSC) with a 22.3% power conversion efficiency (PCE). This is a new performance record for a PSC with an absorber bandgap of 1.63 eV. We demonstrate that the high device performance originates from a synergy between (1) an improved perovskite absorber quality when introducing formamidinium chloride (FACl) as an additive in the “triple cation” Cs0.05FA0.79MA0.16PbBr0.51I2.49 (Cs-MAFA) perovskite precursor ink, (2) an increased open-circuit voltage, V OC, due to reduced recombination losses when using a lithium fluoride (LiF) interfacial buffer layer, and (3) high-quality hole-selective contacts with a self-assembled monolayer (SAM) of [2-(9H-carbazol-9-yl)­ethyl]­phosphonic acid (2PACz) on ITO electrodes. While all devices exhibit a high performance after fabrication, as determined from current–density voltage, J–V, measurements, substantial differences in device performance become apparent when considering longer-term stability data. A reduced long-term stability of devices with the introduction of a LiF interlayer is compensated for by using FACl as an additive in the metal-halide perovskite thin-film deposition. Optimized devices maintained about 80% of the initial average PCE during maximum power point (MPP) tracking for >700 h. We scaled the optimized device architecture to larger areas and achieved fully laser patterned series-interconnected mini-modules with a PCE of 19.4% for a 2.2 cm2 active area. A robust device architecture and reproducible deposition methods are fundamental for high performance and stable large-area single junction and tandem modules based on PSCs.

Two birds with one stone: dual grain-boundary and interface passivation enables >22% efficient inverted methylammonium-free perovskite solar cells

“…Furthermore, we investigate the operational stability of PSCs for which the perovskite/ETL interface is passivated using a thin evaporated LiF layer, which is often employed in high-efficiency p-i-n PSCs. 31,35,38,88,89,93 In comparison with our GBP&SP PSCs (Fig. S42) the p-i-n PSC with LiF passivation layer degrades much faster, reaching 80% of the initial PCE already after 7 h of constant illumination.…”

“…Similar reports on the fast degradation of LiF containing p-i-n PSC can be found in literature. 31,93 Next to improved operational stability under constant AM1.5G illumination, the GBP&SP PSCs demonstrate improved thermal stability as compared to Ref PSCs by tracking the photovoltaic performance of the devices after aging under 85 °C heating in the dark over 1000 h (see Fig 7c). To further evaluate the stability with regard to moisture, we exposed unencapsulated Ref PSCs and GBP&SP PSCs to a relative humidity of ~50% in ambient atmosphere and at room temperature for 1 day.…”

Application of MXenes in Perovskite Solar Cells: A Short Review

“…Currently, a great deal of research is focused on optimizing the performance and enhancing the stability of PSCs. Various approaches have been reported for performance and stability improvement of PSCs such as use of solar concentrators, spectral modification, bandgap engineering, interfacial passivation and modification, solvent manipulation, additive manufacturing, compositional engineering and use of novel materials [ 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ].…”

Two Birds with One Stone: Dual Grain-Boundary and Interface Passivation Enables > 22% Efficient Inverted Methylammonium-Free Perovskite Solar Cells

“…19,25,35,53,67,77,92 Recently, lithium fluoride (LiF) has been identified as an interlayer at the perovskite/ETL interface that significantly enhances the performance of p-i-n PSCs. 31,35,38,88,89,93 However, PSCs with LiF undergo severe long-term degradation which limits the applicability of this approach. 31,93 In order to reduce non-radiative recombination in the bulk and grain boundaries, the use of non-stoichiometric precursors [94][95][96] or incorporation of different additives into the perovskite precursor solution or antisolvent such as metal cations, 97 anions, 98 chloride (Cl) or thiocyanate (SCN), [4][5][6]10,14,15,17,19,88 (alkyl)ammonium salts, 3,25,26,64,[98][99][100][101][102][103][104][105] other organic compounds, 74,84,106 and fluoride-containing materials 74,…”

“…31,35,38,88,89,93 However, PSCs with LiF undergo severe long-term degradation which limits the applicability of this approach. 31,93 In order to reduce non-radiative recombination in the bulk and grain boundaries, the use of non-stoichiometric precursors [94][95][96] or incorporation of different additives into the perovskite precursor solution or antisolvent such as metal cations, 97 anions, 98 chloride (Cl) or thiocyanate (SCN), [4][5][6]10,14,15,17,19,88 (alkyl)ammonium salts, 3,25,26,64,[98][99][100][101][102][103][104][105] other organic compounds, 74,84,106 and fluoride-containing materials 74,107 have been proposed. Given that these additives directly assist in perovskite film formation, changes in crystallization dynamics as well as a reduced defect density are commonly observed.…”