2 research outputs found
On the Uniqueness of Ideality Factor and Voltage Exponent of Perovskite-Based Solar Cells
Perovskite-based solar cells have
attracted much recent research
interest with efficiency approaching 20%. While various combinations
of material parameters and processing conditions are attempted for
improved performance, there is still a lack of understanding in terms
of the basic device physics and functional parameters that control
the efficiency. Here we show that perovskite-based solar cells have
two universal features: an ideality factor close to two and a space-charge-limited
current regime. Through detailed numerical modeling, we identify the
mechanisms that lead to these universal features. Our model predictions
are supported by experimental results on solar cells fabricated at
five different laboratories using different materials and processing
conditions. Indeed, this work unravels the fundamental operation principle
of perovskite-based solar cells, suggests ways to improve the eventual
performance, and serves as a benchmark to which experimental results
from various laboratories can be compared
Efficient Organic Photovoltaics with Improved Charge Extraction and High Short-Circuit Current
Exciton
generation, dissociation, free carrier transport, and charge
extraction play an important role in the short-circuit current (<i>J</i><sub>sc</sub>) and power conversion efficiency of an organic
bulk heterojunction (BHJ) solar cell (SC). Here we study the impact
of band offset at the interfacial layer and the morphology of active
layer on the extraction of free carriers. The effects are evaluated
on an inverted BHJ SC using zinc oxide (ZnO) as a buffer layer, prepared
via two different methods: ZnO nanoparticle dispersed in mixed solvents
(ZnO A) and sol–gel method (ZnO B). The device with ZnO A buffer
layer improves the charge extraction and <i>J</i><sub>sc</sub>. The improvement is due to the better band offset and morphology
of the blend near the ZnO A/active layer interface. Further, the numerical
analysis of current–voltage characteristics illustrates that
the morphology at the ZnO A/active layer interface has a more dominant
role in improving the performance of the organic photovoltaic than
the band offset