  Drop-on-demand inkjet printing is a promising and commercially relevant
technology for producing organic electronic devices of arbitrary shape on a
wide variety of different substrates. In this work we transfer the inkjet
printing process of organic photovoltaic devices from 2D to 3D substrates,
using a 5-axis robot system equipped with a multi nozzle inkjet printing unit.
We present a ready-to-use 3D printing system for industrial application, using
a 5-axis motion system controlled by commercial 3D motion software, combined
with a commonly used multi-nozzle inkjet print head controlled by the
corresponding printing software. The very first time inkjet-printed solar cells
on glass/ITO with power conversion efficiencies (PCE) of up to 7% are realized
on a 3D object with surfaces tilted by angles of up to 60{\deg} against the
horizontal direction. Undesired ink flow during deposition of the
inkjet-printed layers was avoided by proper ink formulation. In order to be
able to print organic (opto-)electronic devices also on substrates without
sputtered indium tin oxide bottom electrode, the bottom electrode was
inkjet-printed from silver nanoparticle (AgNP) ink, resulting in the first all
inkjet-printed (i.e., including bottom electrode) solar cell on a 3D object
ever with a record PCE of 2.5%. This work paves the way for functionalizing
even complex objects, such as cars, mobile phones, or Internet of Things (IoT)
applications with inkjet-printed (opto-)electronic devices.
