Modeling and simulation of band-gap profiling with planar heterojunction of hole-transporting layer-free perovskite solar cells. (13th July 2017)

• Record Type: Journal Article
• Authors: Liu, Yung-Tsung; Chen, Yu-Hung; Lin, Chen-Cheng; Fan, Chia-Ming; Liu, Jun-Chin; Tung, Yung-Liang; Tsai, Song-Yeu
• Is Part Of: Materials research express. Volume 4:Number 7(2017)
• Publication Date: 2017-07-13
• Subjects: perovskite solar cells -- graded band-gap profiles -- hole-transporting layer-free; Materials science -- Research -- Periodicals; Materials science -- Periodicals; 620.11
• DOI: 10.1088/2053-1591/aa77ee
• Languages: English
• ISSNs: 2053-1591

Abstract

Abstract: This study entailed modeling a perovskite absorber involving band-gap grading at the back of the absorber and double-grading profiles of hole-transporting layer-free perovskite solar cells. Device simulation based on continuity equations and Poisson's equation was carried out by using AMPS-1D software. The optimum grading profile consisted of a band gap of 1.7 eV at the interface between the TiO2 and absorber with a graded thickness of 300 nm, uniform 1.5 eV of 50 nm, and back surface 2.1 eV with a graded thickness of 50 nm. The attained simulated efficiency was 22.68% (open-circuit voltage, V oc = 1.34 V; short-circuit current density, J sc = 19.98 mA cm −2 ; fill factor, FF = 0.84), which is close to the uniform band gap of 1.5 eV of the whole absorber with a hole-transporting layer (Spiro-OMeTAD). This was mainly because of back grading forming a conduction band energy barrier to suppress the transportation of photo-generated electrons from the absorber to the back electrode, thereby improving carrier collection. The results indicate that the hole-transporting layer could be replaced by optimal band-gap profiling of the absorber, with near to no decayed performance of the perovskite solar cells.