Annan Zhu

Conflicts of Interest The authors declare no conflicts of interest. Data Availability Statement The data that support the findings of this study are available from the corresponding author upon reasonable request. Supporting Information Filename Description pip_70085-sup-0001-Supporting_information.docxWord 2007 document , 5 MB Figure S1: 1H-NMR spectra of β-Ala-SnI2. Figure S2: 1H-NMR spectra of β-Ala-FAI. Figure S3: (a) SEM images of β-Ala-Sn films with different concentrations.

Conflicts of Interest The authors declare no conflicts of interest. Data Availability Statement The data that support the findings of this study are available from the corresponding author upon reasonable request.

1 Introduction Perovskite solar cells (PSCs) have demonstrated remarkable potential for addressing growing global energy demands.[1] As an efficient and cost-effective photovoltaic technology, a steady increase in the power conversion efficiency (PCE) of PSCs has been achieved, exceeding 26.7%, which is comparable to the highest PCE of single-crystalline silicon solar cells.[2] Although organic electron transport layers (ETLs), such as phenyl-C61-butyric acid methyl ester (PC61BM), have been...