@article{oai:tsukuba.repo.nii.ac.jp:00046718,
 author = {鈴木, 義和 and OKAMOTO, Yuji and YASUDA, Takeshi and SUMIYA, Masatomo and SUZUKI, Yoshikazu},
 issue = {3},
 journal = {Applied Energy Materials},
 month = {Feb},
 note = {In the conventional two-step prepared perovskite solar cells, the CH3NH3PbI3 (MAPbI3) film usually contains an unreacted PbI2 at the interface between an electron transport layer (ETL) and a perovskite active layer. To reduce the unreacted PbI2 in the two-step prepared MAPbI3 film, we have recently reported a new three-step method, which was realized by an additional MA(I,Br) spin-coating. Here, we propose an advanced three-step method, viz., an additional HC(NH2)2I (FAI) spin-coating on the two-step prepared MAPbI3 film. The additional FAI spin-coating formed a FAxMA1–xPbI3 solid solution by the incorporation of FA ion into MAPbI3. Also, the additional FAI spin-coating yielded a FAyMA1–yPbI3 layer (y > x) by converting the unreacted PbI2, which resulted in the layered structure with different FA concentrations and hence, with the multiple bandgap structure. The best PCE of 18.1% was achieved by optimizing the FAI spin-coating process.},
 pages = {1389--1394},
 title = {Perovskite Solar Cells Prepared by Advanced Three-Step Method Using Additional HC(NH2)2I Spin-Coating: Efficiency Improvement with Multiple Bandgap Structure},
 volume = {1},
 year = {2018}
}