THE EFFECT OF BULK-HETEROJUNCTION CLALPC:C60 RATIO ON ORGANIC PHOTODETECTORS WITH NORMAL AND INVERTED STRUCTURE USING VACUUM DEPOSITION

Although it has become an extensive research area, organic photodetectors
(OPDs), which are electromagnetic radiation sensors in the form of photons that
convert optical signals into electrical signals, are still being developed to obtain far
more optimal performance (in terms of detection) so that can be applied in all
sectors. This study contributes to providing a knowledge base on OPDs by
comparing the performance against normal and inverted structures based on BHJ
(ClAlPc:C60) and vacuum deposition with variations in active layer ratios (3:1),
(1:1), (1:3), and (1:0). Performance testing of all devices is carried out by
characterizing current density & current gain, EQE, responsivity, detectivity, as
well as frequency and speed response. As a result, normal structured OPDs with an
active layer dominated by C60 (at a ratio of 1:3 and 1:1) show satisfactory
performance with gains reaching > 7E+05 A/cm2
and detectivity > 1E+12 Jones,
along with sustainability at frequency 300kHz working and transition
response < 2.5 µs. In contrast to the inverted OPDs, which offer their best
performance on devices whose active layer is dominated by ClAlPc (at a ratio of
3:1) with a gain of ~2E+05 A/cm2
and detectivity > 8E+11 Jones, with
sustainability that is not as good as that of a normal device (f-3dB ≈ 270kHz and
transition > 2.6 µs). The dominance of different molecules in the active layer in
each structure offers satisfactory OPDs performance.
Keywords : OPDs, inverted and normal structure, bulk-heterojunction,
ClAlPc:C60, active layer ratio.