Abstract
Organic photovoltaics (OPV), one of the emerging
thin-film photovoltaic technologies, has gained
considerable interest being flexible, light weight and
transparent. OPVs can be processed by using roll-to-roll
(R2R) printing and coating methods which can lead to
significant manufacturing cost reduction. Gravure
printing brings the advantage of layer patterning
directly in the printing process. This differentiates
gravure printing from coating technologies. Importantly,
this increases product design freedom by enabling
large-area arbitrary shape and size structures. This
opens up possibility to use OPVs also as decorative
elements on the surfaces of interior and exterior
building spaces. Secondly, gravure printing enables high
repeatability and accuracy in thin-film deposition.
In this Thesis, the applicability of gravure printing was
demonstrated firstly in the laboratory by using a
standard OPV device configuration. The layer properties
(layer thickness, uniformity) of the gravure-printed hole
transport layer and photoactive layer were optimized by
engineering the printability using printing master
parameters, ink formulations and printing parameters. The
electrical functionality of these printed layers was
studied in organic solar cells using a standard
measurement method. The cells were further connected to
modules. After this, the outlined processing conditions
for OPV modules (active area 15 cm2) were transferred to
R2R pilot production environment. Small pinholes were
found to form readily in the photoactive layer in R2R
gravure printing with a standard cell configuration.
However, by using an ultrathin evaporated insulating
interlayer electrical short-circuit could be inhibited,
leading to considerably improved performance with a
maximum efficiency of 1.9%. In addition, a R2R printing
process for inverted OPV configuration modules was
developed and demonstrated. The device structure
consisted of five layers, which were either gravure or
screen printed. Few hundred fully R2R printed modules
with the active area ranging from 14-97 cm2 were
fabricated with excellent yield. With the 97 cm2 sized
modules an average output power of 0.17W was generated
(power conversion efficiency of 1.8±0.1 %).
The main achievements of this thesis are i) gravure
printing based R2R thin-film deposition technology for
OPV, ii) printed standard and inverted device structures,
iii) R2R manufactured large-area flexible solar modules,
iv) OPV process upscaling to R2R pilot level and v)
investigation of characterization methods for OPV
modules.
Original language | English |
---|---|
Qualification | Doctor Degree |
Awarding Institution |
|
Supervisors/Advisors |
|
Award date | 4 Sept 2015 |
Place of Publication | Espoo |
Publisher | |
Print ISBNs | 978-951-38-8328-7 |
Electronic ISBNs | 978-951-38-8329-4 |
Publication status | Published - 2015 |
MoE publication type | G5 Doctoral dissertation (article) |
Keywords
- roll-to-roll printing
- gravue printing
- organic photovoltaics
- upscaling
- monolithic modules
- printed electronics
- electrical imaging