No abstract

The contributions of photon recycling and light scattering to the performance of perovskite solar cells are quantified.

Mixed-halide perovskites (MHPs) have attracted attention as suitable wide-band-gap candidate materials for tandem applications owing to their facile band-gap tuning. However, when smaller bromide ions are incorporated into iodides to tune the band gap, photoinduced halide segregation occurs, which leads to voltage deficit and photoinstability. Here, we propose an original post-hot pressing (PHP) treatment that suppresses halide segregation in MHPs with a band gap of 2.0 eV. The PHP treatment reconstructs open-structured grain boundaries (GBs) as compact GBs through constrained grain growth in the in-plane direction, resulting in the inhibition of defect-mediated ion migration in GBs. The PHP-treated wide-band-gap (2.0 eV) MHP solar cells showed a high efficiency of over 11%, achieving an opencircuit voltage (V oc ) of 1.35 V and improving the maintenance of the initial efficiency under the working condition at AM 1.5G. The results reveal that the management of GBs is necessary to secure the stability of wide-band-gap MHP devices in terms of halide segregation.

The transient properties of photogenerated carriers using a pulsed laser have been widely used to observe carrier characteristics of perovskite solar cells (PSCs). However, these transient results could not reveal a steady-state operation performance of the PSCs under continuous illumination. Thus, an evaluation of the transporting parameters for perovskite thin films (PTFs) under continuous illumination is needed to understand the operation performance of solar cells. Here, we report that the steady-state transport parameters for the PTF can be extracted through photo-Hall effect measurement (PHEM) by solving the signal uncertainty. We observed that the interaction of atmospheric gas molecules with the PTF causes the uncertainty of opto-electrical results. The uncertainty of signals was overcome by designing a Hall specimen and controlling the surface of the PTF. We characterized two types of PTFs featuring distinct efficiency differences and successfully extracted their transporting parameters in the near-1-sun conditions through the PHEM.