Monodisperse Perovskite Colloidal Quantum Dots Enable High-Efficiency Photovoltaics
Seyeong Lim, Gyudong Lee, Sang‐Hun Han, Jigeon Kim, sunhee Yun, Jongchul Lim, Yong‐Jin Pu, Min Jae Ko, Taiho Park, Jongmin Choi, Younghoon Kim
Abstract
Bandtail broadening originating from increasing the polydispersity of colloidal quantum dots (CQDs) deteriorates open-circuit voltage (VOC) and hinders charge-carrier transport in CQD photovoltaics. The development of colloidal synthetic routes has enabled preparing monodisperse perovskite CQDs (Pe-CQDs) that have attracted attention as promising absorbers in CQD photovoltaics. However, polar-antisolvent-based purification induces the dissolution and agglomeration of Pe-CQDs, resulting in an irregular size distribution. Consequently, the photovoltaic performance decreases because of the increase in Pe-CQD polydispersity. Here, we demonstrate the preparation of well-purified monodisperse CsPbI3-Pe-CQDs via size selection on the basis of gel permeation chromatography. Well-purified monodisperse Pe-CQDs exhibit improved photovoltaic performance and achieve a low Pe-CQD polydispersity. Furthermore, these Pe-CQDs show higher photoluminescence quantum yields, narrower full-widths at half-maximum, and lower Urbach energies, in comparison to irregular-sized Pe-CQDs without size selection. Therefore, CsPbI3-Pe-CQD solar cells comprising monodisperse Pe-CQDs show the highest power conversion efficiency (15.3%) and VOC (1.27 V) among the fully inorganic CsPbI3-Pe-CQD solar cells reported so far.