posted on 2018-08-27, 00:00authored byShuzhang Yang, Xuezhi Song, Liguo Gao, Ning Wang, Xiaogang Ding, Shufeng Wang, Tingli Ma
Reducing
the energy barriers for charge carrier injection, extraction,
or transport within both electron- and hole-transporting interfaces
is crucial for minimizing charge carrier transport losses in perovskite
solar cells (PSCs). In this Article, an ultrafast, solution-processed
hydroxide semiconductor material, called Nb(OH)5, which
has a similar energy band and transparency to its crystallization,
Nb2O5, is first used as an electron transport
layer (ESL) for PSCs. The conductivity of the Nb(OH)5 is
lower than that of Nb2O5; however, a power conversion
efficiency (PCE) of approximately 13.62% is obtained by fully fabricating
devices at room temperature with a MAPbI3 light absorption
layer, which is almost the same as that of PSCs based on Nb2O5. The performance of the fabricated device shows that
the Nb(OH)5 film has seamless contact with the fluorine-doped
tin oxide (FTO) substrate. The conductivity of the Nb2O5 film is 4 orders larger than that of Nb(OH)5;
however, a low interfacial barrier results in interfacial resistance
between the Nb(OH)5 and FTO substrate that is 3–4
orders lower than that of Nb2O5 due to universal
quasi-ohmic contacts. By comparing with properties of PSCs with different
ESLs (Nb(OH)5 and Nb2O5), a further
efficient electron extract principle from the perovskite layer to
FTO substrate is promoted. The PCE of PSCs still needs to be improved
further; however, this solution-processed hydroxide semiconductor
material, Nb(OH)5, has shown numerous benefits to PSCs
with ultrafast process, low cost, and large-area fabrication.