Surface passivation of sequentially deposited perovskite solar cells by octylammonium spacer cations

Abstract

Effective passivation of defects is an important step toward achieving highly efficient and stable Perovskite Solar Cells (PSCs). In this work, we introduce the incorporation of two different octylammonium based spacer cations as 2D perovskite passivation layers, namely Octylammonium Bromide (OABr) and octylammonium iodide. PSCs with OABr as a 2D passivation layer demonstrated an enhanced Power Conversion Efficiency (PCE) of 21.40% (the control device has a PCE of 20.26%), resulting in a higher open circuit voltage of 40 mV. The 2D perovskite passivation layers lead to a smoother interface and a better contact with the hole transport layer, while transient photoluminescence and transient photovoltage measurements indicated reduced non-radiative recombination. Unencapsulated devices retained almost 90% of their initial PCE after 500 h of exposure under high ambient humidity conditions, confirming that the surface passivation treatment has led to improved device stability.

Improved Performance of Hole-Transporting Material-Free Perovskite Solar Cells Using a Low-Temperature Printed Carbon Paste

“…The best-performing device with the 2D layer yielded a PCE of 14.83%, a V OC of 0.94 V, a J SC of 23.7 mA cm –2 , and an FF of 66.6% while the device without the 2D layer had a PCE of 12.88%, a V OC of 0.9 V, a J SC of 23.4 mA cm –2 , and a FF of 61.2% (Figure S2). In our previous work, we have demonstrated the effective passivation of the perovskite layer, by incorporating OABr as a 2D passivation layer between the perovskite and the HTL, resulting in enhanced efficiency and V OC of the devices . As mentioned in recent literature, 2D perovskites have significant electron-blocking properties thus substantially reducing interfacial recombination losses .…”

“…In our previous work, we have demonstrated the effective passivation of the perovskite layer, by incorporating OABr as a 2D passivation layer between the perovskite and the HTL, resulting in enhanced efficiency and V OC of the devices. 23 As mentioned in recent literature, 2D perovskites have significant electronblocking properties thus substantially reducing interfacial recombination losses. 22 The current experiments of mesoscopic HTL-free printable C-PSCs have also confirmed those results, and therefore, we will use the 3D/2D passivated perovskite for the rest of the experiments that will be performed in this study.…”

“…Since LTPC-CEs may be directly deposited atop the perovskite, they do not have to face the issues associated with HTPC-CEs, such as insufficient perovskite impregnation and morphological control. The high interest in C-PSCs has led to the development of various optimization approaches, including the implementation of thin electron blocking layers (EBLs) between perovskite and C-CE and the passivation of perovskite active layers . Recent advancements in C-PSCs have included graphene-doped P3HT as an HTM, achieving exceptional PCEs above 18%, as well as extended shelf stability of 1600 h and operational stability of 600 h under 1-sun illumination …”

“…The high interest in C-PSCs has led to the development of various optimization approaches, including the implementation of thin electron blocking layers (EBLs) between perovskite and C-CE 22 and the passivation of perovskite active layers. 23 Recent advancements in C-PSCs have included graphene-doped P3HT as an HTM, achieving exceptional PCEs above 18%, as well as extended shelf stability of 1600 h and operational stability of 600 h under 1-sun illumination. 24 A strategy to reduce performance losses at the perovskite/ HTM or perovskite/CE interfaces is to passivate the perovskite surface.…”

Effect of Br Ions in Octylammonium 2D Perovskites for Performance Improvement of CuSCN-Based Perovskite Solar Cells

“…This study investigated the possibility of protecting perovskites from DES using 2-dimensional (2D) perovskites. Recently, the surfaces of light-harvesting perovskites (3-dimensional (3D) perovskites) have been treated with ammonium cations with large ionic radii (e.g., 2-phenylethylammonium (PEA), n -butylammonium, and n-octylammonium (OA)) to form 2D perovskites. Because 2D perovskites containing large ammonium cations are more stable than 3D perovskites, they function as protective layers and suppress the degradation of 3D perovskites by atmospheric moisture and heat .…”