Effect of Steric Hindrance of Butylammonium Iodide as Interface Modification Materials on the Performance of Perovskite Solar Cells

Abstract

The efficiency and stability of perovskite solar cells (PSCs) can be effectively improved by interfacial modification with butylammonium iodide (BAI). However, the steric hindrance of BAI is not explored. Herein, BAI with different steric hindrances, that is, n‐BAI, iso‐BAI (i‐BAI), and tert‐BAI (t‐BAI), are systematically studied as interface modification materials between (FAPbI3)0.95(MAPbBr3)0.05 and spiro‐OMeTAD in PSCs. It is found that the efficiency and humidity stability of devices gradually increase in the order of t‐BAI‐, i‐BAI‐, n‐BAI‐modified ones. This seems that the larger steric hindrance hinders BAI diffusion to the grain boundary, resulting in the reduction of grain boundary passivation and the residue of excessive BAI on the surface of perovskite films. Excessive BAI is equivalent to new defects and can block hole transport. As the steric hindrance increases from n‐BAI to i‐BAI, and further to t‐BAI, the device with n‐BAI modification shows the highest power conversion efficiency (PCE) of 20.67% with excellent stability in air with a humidity of 20–30%, keeping 80% of the original PCE after 60 days. It is believed that this study can guide the structural selection of modified materials at the interface between perovskite and hole transport layer with n–i–p structure.

Machine-Learning-Assisted Screening of Interface Passivation Materials for Perovskite Solar Cells

“…We further collected the PCE improvement ratios of certain ammonium iodides from the literature data set ,− and compared them with our model predictions, as shown in Figure c. The predicted results sufficiently agree with the reported results in the literature.…”

“…Their molecular feature values are shown in Tables S5 and S6, respectively. It is encouraging to find that several salts from the top-10 ammonium iodides were shown to greatly improve the efficiency of PSCs in recent reports. − …”

“…(b) Prediction vs ground truth plot for the ensemble model. (c) Comparison of the prediction and literature PCE enhancement ratio with the same device architecture. ,− …”

Surface Reconstruction for Efficient and Stable Monolithic Perovskite/Silicon Tandem Solar Cells with Greatly Suppressed Residual Strain

“…[22] Thus, during the conventional BAI treatment, few A-sites are active for the substitution of BA cations at the surface. Additionally, due to the relatively long chain length and steric hindrance, [31,32] only a small amount of BA cations can diffuse into the film bulk along the grain boundaries, thus resulting in a limited A-site incorporation. However, the situation is quite different for the sample with DSR treatment.…”

Chemi‐Mechanically Peeling the Unstable Surface States of α‐FAPbI3

“…The surface modification by introducing organic components such as phenethylamine iodide (PEAI), benzylamine (BA), so-butylammonium iodide (IBAI), and conjugated polymer PTQ10 have been attempted on the surface of FAPbI 3 perovskite films to passivate the surface defects and enhance the durability. [25][26][27][28] However, the trade-off between surface conductance and passivation effect needs to be specifically tailored to guarantee both high conversion efficiency and stability.…”