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Article http://pubs.acs.org/journal/acsodf
High-Efficiency Double Absorber PbS/CdS Heterojunction Solar Cells by Enhanced Charge Collection Using a ZnO Nanorod Array Deuk Ho Yeon,†,‡,∥ Bhaskar Chandra Mohanty,§,∥ Che Yoon Lee,†,∥ Seung Min Lee,† and Yong Soo Cho*,† †
Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Korea R&D Center, LG Display Co., Ltd., Paju-si 10845, Gyeonggi-do, Korea § School of Physics and Materials Science, Thapar University, Patiala 147004, India ‡
S Supporting Information *
ABSTRACT: The device architecture of solar cells remains critical in achieving high photoconversion efficiency while affordable and scalable routes are being explored. Here, we demonstrate a scalable, low cost, and less toxic synthesis route for the fabrication of PbS/CdS thin-film solar cells with efficiencies as high as ∼5.59%, which is the highest efficiency obtained so far for the PbS-based solar cells not involving quantum dots. The devices use a stack of two band-aligned junctions that facilitates absorption of a wider range of the solar spectrum and an architectural modification of the electron-accepting electrode assembly consisting of a very thin CdS layer (∼10 nm) supported by vertically aligned ZnO nanorods on a ∼50 nm thick ZnO underlayer. Compared to a planar electrode of a 50 nm thick CdS film, the modified electrode assembly enhanced the efficiency by ∼39% primarily due to a significantly higher photon absorption in the PbS layer, as revealed by a detailed three-dimensional finite difference time-domain optoelectronic modeling of the device.
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INTRODUCTION Solution-processed PbS-based thin-film solar cells have drawn tremendous research interest in recent years for their potential in large area, high throughput, and affordable solar energy conversion.1−5 Intensified research has culminated in a remarkable progress in the photoconversion efficiency (PCE) from
