A Review on Contemporary Hole Transport Materials …
157
devices gave an efficiency of 10.7% but degraded within 24 h and PMMA:P3HT
(90:10) degraded slowly under rigorous condition (99% > RH).
3.2 PEDOT: PSS
PEDOT: PSS (poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) sulfonic
acid) has been widely used as an HTM in inverted planar configurations. PEDOT:PSS
has excellent photovoltaic properties compared to inorganic HTMs. The use of
PEDOT:PSS was first reported by Chen et al., when they used PEDOT:PSS in
PSC made of CH 3 NH 3 PbI 3 perovskite film. The configuration of the PSC was
glass/indium titanium oxide ITO/PEDOT:PSS/CH 3 NH 3 PbI 3 /fullerene(C60)/thin
bathocuproine (BCP) aluminum/(Al). They obtained a modest PCE of 3.9% which
was much lower than highest PCE obtained before (Jeng et al. 2013).
An inverted planar configuration was used by Heo et al. (2015) to fabricate a MAPbI 3 PSC with PEDOT:PSS as a HTM. A configuration of
ITO/PEDOT:PSS/MAPbI 3 /PCBM/Au was adopted by them to get an efficiency of
18%. This type of PSC exhibited better stability and efficiency than other conventional MAPbI 3 devices owing to addition of PCBM as an electron-extracting layer
(Heo et al. 2015).
Recently, Chiang and co-workers used PEDOT:PSS as an HTM in an inverted
planar in CH 3 NH 3 PbI 3 absorber cell. H 2 O, as an additive in the PbI2/DMF precursor
solution, and DMF vapor treatment were combined to prepare thick perovskite layer
(500 nm) with smooth surface and large grain size. Two-step spin coating was used
to prepare CH 3 NH 3 PbI 3 absorber layer. This combined synergistic effect of H 2 O
and DMP vapor treatment resulted in maximum PCE exceeding 20% and the PSC
showed no hysteresis, either in ambient air or nitrogen glove box (Chiang et al. 2017).
3.3 PTAA
Heo et al. (2013) introduced a novel structure incorporating the use of polytriarylamine (PTAA) as the HTM in PSC. PTAA as an HTM was compared
with other PSC containing polymeric HTM (P3HT poly-3-(hexylthiophene)),
PCPDTBT
(poly-[2,1,3-benzothiadiazole-4,7-diyl[4,4-bis(2-ethylhexyl)-4Hcyclopenta
octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl2,1,3-benzothiadiazole4,7-diyl-2,5-thiophenediyl]), and PSCs with no HTM. The device configuration was
FTO/TiO 2 /mpTiO 2 /CH 3 NH 3 PbI 3 /HTM/Gold electrode (Heo et al. 2013). The PCE
of PTAA was reportedly the highest (9%) with highest J sc of 16.4 mA/cm
2 . This
could be attributed to PTAA’s higher hole mobility than other polymeric HTMs
which lead to better interaction with CH 3 NH 3 PbI 3 . Interestingly, PSC with no HTM
had the lowest efficiency and JV characteristics (Fig. 9).
157
devices gave an efficiency of 10.7% but degraded within 24 h and PMMA:P3HT
(90:10) degraded slowly under rigorous condition (99% > RH).
3.2 PEDOT: PSS
PEDOT: PSS (poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) sulfonic
acid) has been widely used as an HTM in inverted planar configurations. PEDOT:PSS
has excellent photovoltaic properties compared to inorganic HTMs. The use of
PEDOT:PSS was first reported by Chen et al., when they used PEDOT:PSS in
PSC made of CH 3 NH 3 PbI 3 perovskite film. The configuration of the PSC was
glass/indium titanium oxide ITO/PEDOT:PSS/CH 3 NH 3 PbI 3 /fullerene(C60)/thin
bathocuproine (BCP) aluminum/(Al). They obtained a modest PCE of 3.9% which
was much lower than highest PCE obtained before (Jeng et al. 2013).
An inverted planar configuration was used by Heo et al. (2015) to fabricate a MAPbI 3 PSC with PEDOT:PSS as a HTM. A configuration of
ITO/PEDOT:PSS/MAPbI 3 /PCBM/Au was adopted by them to get an efficiency of
18%. This type of PSC exhibited better stability and efficiency than other conventional MAPbI 3 devices owing to addition of PCBM as an electron-extracting layer
(Heo et al. 2015).
Recently, Chiang and co-workers used PEDOT:PSS as an HTM in an inverted
planar in CH 3 NH 3 PbI 3 absorber cell. H 2 O, as an additive in the PbI2/DMF precursor
solution, and DMF vapor treatment were combined to prepare thick perovskite layer
(500 nm) with smooth surface and large grain size. Two-step spin coating was used
to prepare CH 3 NH 3 PbI 3 absorber layer. This combined synergistic effect of H 2 O
and DMP vapor treatment resulted in maximum PCE exceeding 20% and the PSC
showed no hysteresis, either in ambient air or nitrogen glove box (Chiang et al. 2017).
3.3 PTAA
Heo et al. (2013) introduced a novel structure incorporating the use of polytriarylamine (PTAA) as the HTM in PSC. PTAA as an HTM was compared
with other PSC containing polymeric HTM (P3HT poly-3-(hexylthiophene)),
PCPDTBT
(poly-[2,1,3-benzothiadiazole-4,7-diyl[4,4-bis(2-ethylhexyl)-4Hcyclopenta
octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl2,1,3-benzothiadiazole4,7-diyl-2,5-thiophenediyl]), and PSCs with no HTM. The device configuration was
FTO/TiO 2 /mpTiO 2 /CH 3 NH 3 PbI 3 /HTM/Gold electrode (Heo et al. 2013). The PCE
of PTAA was reportedly the highest (9%) with highest J sc of 16.4 mA/cm
2 . This
could be attributed to PTAA’s higher hole mobility than other polymeric HTMs
which lead to better interaction with CH 3 NH 3 PbI 3 . Interestingly, PSC with no HTM
had the lowest efficiency and JV characteristics (Fig. 9).