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This content will become publicly available on May 7, 2019

Title: Overcoming the Photovoltage Plateau in Large Bandgap Perovskite Photovoltaics

Development of large bandgap (1.80-1.85 eV Eg) perovskite is crucial for perovskite-perovskite tandem solar cells. However, the performance of 1.80-1.85 eV Eg perovskite solar cells (PVKSCs) are significantly lagging their counterparts in the 1.60-1.75 eV Eg range. This is because the photovoltage (Voc) does not proportionally increase with Eg due to lower optoelectronic quality of conventional (MA,FA,Cs)Pb(I,Br)3 and results in a photovoltage plateau (Voc limited to 80% of the theoretical limit for ~1.8 eV Eg). Here, we incorporate phenyl- ethylammonium (PEA) in a mixed-halide perovskite composition to solve the inherent material-level challenges in 1.80-1.85 eV Eg perovskites. The amount of PEA incorporation governs the topography and optoelectronic properties of resultant films. Detailed structural and spectroscopic characterization reveal the characteristic trends in crystalline size, orientation, and charge carrier recombination dynamics and rationalize the origin of improved material quality with higher luminescence. With careful interface optimization, the improved material characteristics were translated to devices and Voc values of 1.30-1.35 V were achieved, which correspond to 85-87% of the theoretical limit. Using an optimal amount of PEA incorporation to balance the increase in Voc and the decrease in charge collection, a highest power conversion efficiency of 12.2% was realized. Our results clearly overcomemore » the photovoltage plateau in the 1.80-1.85 eV Eg range and represent the highest Voc achieved for mixed-halide PVKSCs. This study provides widely translatable insights, an important breakthrough, and a promising platform for next- generation perovskite tandems.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [1] ; ORCiD logo [1] ; ORCiD logo [2]
  1. Univ. of Washington, Seattle, WA (United States)
  2. Univ. of Washington, Seattle, WA (United States); City Univ. of Hong Kong (China)
Publication Date:
Grant/Contract Number:
EE0006710
Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 18; Journal Issue: 6; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Research Org:
Univ. of Washington, Seattle, WA (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; Tandem solar cell; optoelectronic quality; 2D−3D perovskite; charge recombination dynamics; mixed-halide phase segregation; open-circuit voltage bottleneck
OSTI Identifier:
1436489