Temperature‐Insensitive Efficient Inorganic Perovskite Photovoltaics by Bulk Heterojunctions

Inorganic perovskite solar cells (IPSCs) emerge as ideal candidate for applications beyond terrestrial implementation due to their robustness. However, underlying mechanisms regarding their photovoltaic process at different temperatures remain unclear. Based on a stable absorber of CsPbI2.85(BrCl)0.15, we reveal considerable variation of corresponding device performance over temperature and further demonstrate a simple approach to an effective reduction of such variation. Interestingly, this absorber is found to be excitonic with poor carrier transport even at ambient temperature of 285 K and below. With a novel device configuration of PTB7-th/perovskite bulk heterojunction (BHJ), it facilitates exciton dissociation and carrier extraction. The resultant solar cell attains a best power conversion efficiency (PCE) of 17.2% with the fill factor of 84%, which is the highest efficiency γ-phase IPSCs reported to date. Importantly, this device is less sensitive to operation temperature, wherein the PCE variation over the temperature range from 210 K to 360 K is 60% suppressed compared with the reference. The approach has been effectively extended to other IPSCs with different photo-active phase, which may shed light on realizing highly efficient IPSCs for specific scenarios such as polar regions, near space and exoplanet exploration. This article is protected by copyright. All rights reserved