Increased monodispersity of perovskite colloidal quantum dots enabling high-efficiency solar cells
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Bandtail broadening due to the polydispersity of quantum dots (QDs) results in the deterioration of VOC and charge-carrier transport in QD photovoltaics. The development of perovskite QDs (PQDs), which have recently been attracting attention as a promising absorber in photovoltaics; however, polar-solvent-based purifications result in the irregular size-distribution of PQDs and lead to the increase in polydispersity. Here, we report that monodisperse PQDs can be achieved through the size-selection process and improve the photovoltaic performance because of the decrease in polydispersity and bandtail sharpening. Monodisperse PQDs show higher PLQY, narrower FWHM and lower Urbach energy, compared to irregular-size PQDs. Therefore, CsPbI3 PQD solar cells based on monodisperse PQDs improve up to a PCE of 15.3% with a VOC of 1.27 V.