Tunneling‐Assisted Trapping as one of the Possible Mechanisms for the Origin of Hysteresis in Perovskite Solar Cells

Abstract

Perovskite solar cells (PSCs) are among the promising candidates to reach the highest efficiency among single‐junction solar cells due to their band gap around 1.55 eV, strong absorption, and long charge carrier diffusion length. However, the anomalous hysteresis observed in its current–voltage (I–V) curves that creates confusion about the true efficiency has been a serious drawback for further improvement of its stable power output. Hence, understanding the origin of the I–V hysteresis is important and has been discussed widely in recent publications. Herein, the hysteresis in the I–V curves of PSCs has been studied by using a two‐dimensional model employing the Silvaco Atlas software. The study was performed using planar structure cells made of fluorine‐doped tin oxide glass substrate (FTO), a compact‐titanium‐oxide (c‐TiO2) electron‐transport layer, methylammonium lead triiodide (MAPbI3) layer, 2,2′,7,7′‐tetrakis‐(N,N‐di‐4‐methoxyphenylamine)‐9,9′‐spirobifluorene (spiro‐OMeTAD) hole‐transport layer and gold back contact. The effect of trap‐assisted charge accumulation in c‐TiO2 and recombination at the c‐TiO2/MAPbI3 interface on the I–V curves is assessed. The study shows that these two processes can reproduce the hysteresis behavior as a function of the scan rate and voltage preset in PSCs. Also, this study suggests that decreasing charge trapping and recombination at the c‐TiO2/MAPbI3 interface could be important to reduce hysteresis and improve the PSC efficiency.

Halide Perovskite Photovoltaics: Background, Status, and Future Prospects

“…The use of organic electron transport layers like PCBM or C60 , and modification of the most widely used TiO 2 ETM layer surface with organic molecules − have become popular interface engineering strategies to reduce J–V hysteresis. While a majority of recent studies suggest ion migration to be responsible for such anomalous hysteresis, − some other studies claim that traps at the interface and interfacial recombination cause the hysteresis. − Possible mechanisms of origin of hysteresis and methods of reduction/elimination of hysteresis are thoroughly discussed in book chapters and also in some review articles. , …”

Material challenges for solar cells in the twenty-first century: directions in emerging technologies

“…This model presented in Figure 20 (a) can reproduce the large hysteresis observed in experimental data as it can be seen in Figure 20 (b). We are now working on understanding the capacitance origin using the software SILVACO ATLAS [ 209 ].…”

High-Efficiency Flexible Perovskite Solar Cells Enabled by an Ultrafast Room-Temperature Reactive Ion Etching Process

“…This diminished hysteresis behavior was also observed with large-area PSCs (active areas of 0.56 and 1.05 cm 2 ), as shown in Figure S1. In general, large hysteresis is often observed with typical TiO 2 ETL-based PSCs, and the origin of the phenomenon has been considered to be the large charge accumulation at the TiO 2 /perovskite interface, which leads to a low charge extraction . Therefore, we performed photoluminescence (PL) measurements to examine the electron extraction properties of the HT- and RIE-mp-TiO 2 layers.…”