Preparation of High-Efficiency All-Perovskite Tandem Solar Cells

Although the efficiency of the organic-inorganic hybrid perovskite solar cell (PSCs) has reached 26.2%, it still has not surpassed silicon-based solar cells. At the same time, poor stability also makes the competitiveness of single-layer PSCs not obvious compared with silicon solar cells. Since 2015, narrow bandgap PSCs have been widely reported due to their better light absorption. However, wide bandgap perovskites should not be neglected as they are important for fabricating tandem PSCs. Here, we demonstrate a series of monolayer molecules with different alkyl chain lengths as interfacial modifiers to modify the PTAA and perovskite layer for improving the optoelectronic properties of PSCs by improving the quality of perovskite films and increasing the transport and extraction of interfacial carriers. The target device achieves a PCE of 16.57%, which is one of the highest PCE of the WBG-PSCs. Besides, the all-perovskite tandem solar cells with the WBG-Pb-perovskite solar cells and the narrow bandgap Sn/Pb perovskite solar cells gave a high PCE of 25.24%.<br/>Here, we fabricated the wide bandgap PSCs with or without SAM modification. We found that the champion control device with a PCE of 14.46% (a short circuit current (<i>J</i>_SC) of 17.15 mA/cm², an open-circuit voltage (<i>V</i>_OC) of 1.117 V, and a fill factor (FF) of 75.53%), while the devices based on 3,3PrPACz, 4,3BuPACz, and 6,3HePACz modification got the highest PCE of 15.49% (a <i>J</i>_SC of 17.59 mA/cm², a <i>V</i>_OC of 1.141 V and an FF of 77.20%), 16.57%, and 15.29%, respectively. According to the corresponding incident photon-to-electron conversion efficiency (IPCE) spectra of the best-performing control device and PTAA/monolayer molecules devices, with the integrated current densities of 16.99 mA/cm² for the control device, 17.34 mA/cm² for the 3,3PrPACz-modified device, in good agreement with the <i>J-V</i> characterization. Finally, all-perovskite tandem solar cells were fabricated further to improve the PCE of PSCs. The <i>J-V</i> curves of all perovskite tandem solar cells modified by 3,3PrPACz show a high PCE of 25.24% was obtained (a <i>J</i>_SC of 17.115 mA/cm², a <i>V</i>_OC of 1.814 V, and an FF of 81.3%) with forward scan and 24.50% with reverse scan (a <i>J</i>_SC of 17.161 mA/cm², a <i>V</i>_OC of 1.800 V and an FF of 79.3%), which shows the negligible hysteresis. &lt;div id="gtx-trans" style="position: absolute; left: 485px; top: 401.594px;"&gt; &lt;div class="gtx-trans-icon"&gt; &lt;/div&gt; &lt;/div&gt;