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Unrevealing Charge Carrier Selective Layer in Silicon Heterojunction Solar Cells via Multifunctional Atomic Force Probes
Author(s) -
Wang Yusheng,
Xia Zhouhui,
Wu Haihua,
Li Shaojuan,
Wang Tao,
Sun Baoquan
Publication year - 2019
Publication title -
solar rrl
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.544
H-Index - 37
ISSN - 2367-198X
DOI - 10.1002/solr.201900312
Subject(s) - pedot:pss , materials science , passivation , heterojunction , optoelectronics , silicon , charge carrier , polymer solar cell , dielectric , kelvin probe force microscope , nanotechnology , solar cell , layer (electronics) , atomic force microscopy
The current silicon solar cell with a record efficiency is based on heterojunction contacts that offer carrier selectivity as well as surface passivation simultaneously. One remaining challenge with heterocontacts is the balance between carrier extraction and surface passivation. Here, it is demonstrated that the heterojunction of n‐type silicon (N–Si) with the conducting polymer poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) removes this trade‐off, utilizing the strong depletion of PEDOT:PSS to realize the excellent carrier selectivity. The near‐field optical contrast and surface potential distributions of the PEDOT:PSS/N–Si heterojunction via multifunctional atomic force probes are mapped for the first time. Interestingly, a low dielectric value region is observed in N–Si by using scattering‐type scanning near‐field optical microscopy on the junction cross‐section. A special PEDOT:PSS slope is further fabricated to characterize the dielectric value and surface potential in the PEDOT:PSS side. By combining s‐SNOM and scanning Kelvin probe microscopy, a special region in PEDOT:PSS is observed with a sharp surface potential drop and low dielectric value. The results suggest the existence of space charge regions both in N–Si and PEDOT:PSS at the interface. These findings contribute the understanding of the physical properties of the silicon heterojunction and promise potential routes to enhance device efficiency.