Constructing moisture-stable hybrid perovskite-type semiconductors based on hydrogen-bond-free strategy
【摘要】：Hybrid perovskites-type light absorbers, notably based on methylammonium or formamidinium, have promising application in optoelectronics; however they are notorious for their characteristic low moisture stabilities and monotonous band gaps. Constructing new stability-enhanced hybrid lead iodine perovskites(HLIPs) with desired band gaps is imperative, but still a critical challenge. Herein, we demonstrate two effective strategies, which provide new ways to solve the above two issues. The "hydrogen-bond-free" strategy is aimed to enhance the stability of HLIPs by prohibiting organic components from forming strong hydrogen bonds with external water molecules. The "dual-iodine" strategy is towards the synthesis of stable HLIPs with reduced band gaps, which indicates that the I-coordinated metal complex can strongly reconstruct both the bottom of conduction bands(CBs) and the top of valence bands(VBs) of inorganic lead iodines skeleton to reduce the band gaps. As a proof-of-concept application, ambient-stable HLIPs(1,1'-diethyl-[2,2'-bipyridine]-1,1'-diium)Pb3 I8(denoted as EtBpy-Pb3 I8) and [Cu(2,2'-bipyridine)2 I]2 Pb2 I6(denoted as CuIBpy-Pb2 I6) are synthesized, which can endure relative humidity(RH) of 100% and sunlight irradiation at least 60 days. Both EtBpy-Pb3 I8 and CuIBpy-Pb2 I6 show good photoconduction behavior with short rise and decay recovery time, and exhibit excellent repeatabilities of photocurrent. This work not only provides two new promising stability-enhanced lead-based semiconductors for light absorption application, but also opens the new ways to enhance the stabilities and tune the band gaps of HLIPs.