Publication date: 8th January 2019
Organic inorganic (hybrid) perovskite solar cells are considered one of the most promising technologies for future photovoltaics, due to the fast rise of the achievable power conversion efficiency (PCE). The highest power conversion efficiencies obtained recently in literature are via solution-processing, but fully vacuum deposited solar cells are in the same league and able to surpass this record value. The main counterpart of this technique is the presence of doped organic electron/hole transporters, which are not stable at high temperatures nor for long periods of time.
In our previous work we replaced the doped N layer in NiP configuration reducing the parasitical absorption reaching PCEs higher than 20%, but we still relied on a doped P layer. In this work we replace this doped P layer in our PiN and NiP configurations with Molybdenum oxide. MoO3 is an interesting material due to its low lying conduction band which allows hole transport and also due to its low parasitic absorption and stability. We are able to deposit it via vacuum sublimation without any requirement of annealing by changing its WF through an interfacial modification, mantaining opened the possibility of using flexible substrates or being used in tandem solar cells. We are also able to deposit it in our inverted structure without compromising the already deposited layers, reaching power conversion efficiencies higher than 18% in both cases.