High Open Circuit Voltage Over 1 V Achieved in Tin‐Based Perovskite Solar Cells with a 2D/3D Vertical Heterojunction

Abstract

2D-3D mixed tin halide perovskites are outstanding candidate materials for lead-free perovskite solar cells (PSCs) due to their improved stability and decreased trap density in comparison with their pure 3D counterparts. However, the mixture of multiple phases may lead to poor charge transfer across the films and limit the device efficiency. Here, a stacked quasi-2D (down)-3D (top) double-layered structure in perovskite films prepared via vacuum treatment is demonstrated, which can result in a planar bilayer heterojunction. In addition, it is found that the introduction of guanidinium thiocyanate (GuaSCN) additive can improve the crystallinity and carrier mobility in the 2D perovskite layer and passivate defects in the whole film, leading to a long carrier lifetime (>140 ns) in photoluminescence measurements. As a result, the PSCs show a high open circuit voltage (V OC ) up to 1.01 V with a voltage loss of only 0.39 V, which represents the record values ever reported for tin-based PSCs. The champion device exhibits a power conversion efficiency (PCE) of 13.79% with decent stability, retaining 90% of the initial PCE for 1200 h storage in N 2 -filled glovebox.

Nondestructive Post-Treatment Enabled by In Situ Generated 2D Perovskites Derived from Multi-ammonium Molecule Vapor for High-Performance 2D/3D Bilayer Perovskite Solar Cells

“…The PSC based on the control 3D perovskite film delivers a PCE of 17.99% with a short-circuit current density ( J sc ) of 21.10 mA cm –2 , a fill factor ( FF ) of 79.75%, and an open-circuit voltage ( V oc ) of 1.07 V. After the MAM vapor post-treatment, PSCs based on the 2D/3D bilayer perovskite films all exhibit obviously enhanced PCEs. As expected, a significant PCE improvement can be obtained in the PSC based on the PEHA film, which delivers the highest PCE of 21.79% with a J sc of 22.63 mA cm –2 , a FF of 84.90%, and a V oc of 1.13 V. Such notably enhanced PCE can be attributed to the improved photocarrier separation and suppressed carrier recombination induced by the 2D/3D bilayer perovskites. , At the same time, the incident photo-to-current efficiency (IPCE) spectra for the best-performing PSCs are shown in Figure c. The integrated J sc values calculated from IPCE spectra is 20.07, 20.43, 21.02, 21.65, and 22.21 mA cm –2 for PSC based on the control, DETA, TETA, TEPA, and PEHA film, respectively, which agree well with the measured J sc values from J–V curves.…”

Multidentate Chelation Heals Structural Imperfections for Minimized Recombination Loss in Lead‐Free Perovskite Solar Cells

“…[13,14] Until now, the PCEs of Sn-based PSCs (Sn-PSCs) have been lifted to exceed 14 %, by means of composition tailoring, [15,16] interface modification, [17,18] additive engineering, [19][20][21] and processing optimization. [22][23][24][25] However, one could notice most of the state-of-the-art Sn-PSCs still suffered from unsatisfying photovoltage (V oc , normally < 0.9 V) and fill factor (FF, normally < 0.72), which largely limited the further enhancement of device performance.…”

Sn‐Based Perovskite Halides for Electronic Devices

“…With such beneficial aspects, the TPSCs fabricated by this method with PEA 2 FA n− 1 Sn n I 3n+ 1 (n = 10) showed a high V OC of 1.01 V, which minimizes the V OC loss of any type of TPSCs to 0.39 V (Table 5). [208]…”