Improving Hole‐Conductor‐Free Fully Printable Mesoscopic Perovskite Solar Cells’ Performance with Enhanced Open‐Circuit Voltage via the Octyltrimethylammonium Chloride Additive

Abstract

Hole‐conductor‐free fully printable mesoscopic perovskite solar cells (MPSCs) based on mp‐TiO2/mp‐ZrO2/carbon triple mesoscopic layers are competitive candidates among various rapidly developed PSCs for future photovoltaic applications due to the characteristics of low‐cost, easy upscaling, and superior stability. However, the open‐circuit voltage (VOC) loss in printable MPSCs is relatively large compared to that in conventional PSCs, deteriorating the power conversion efficiency (PCE). Herein, the VOC loss is reduced by the octyltrimethylammonium chloride (OTAC) additive. OTAC is found to upshift the Fermi level of TiO2 and passivate trap states in bulk MAPbI3 perovskite, thus optimizing the energy‐level alignment of the TiO2/perovskite heterojunction and suppressing nonradiative recombination in devices. As a result, MPSCs deliver the highest PCE of 16.53% with an improved VOC of 1007 mV. The work demonstrates a facile strategy to reduce the VOC loss in printable MPSCs by simultaneously optimizing the energy‐level alignment and suppressing nonradiative recombination.

Halogen Bond Involved Post‐Treatment for Improved Performance of Printable Hole‐Conductor‐Free Mesoscopic Perovskite Solar Cells

“…The value equals unity when all the carriers recombine directly and gradually approaches two with the increasing severity of trap‐assisted recombination. [ 29 ] The n value was closer to unity in the BFN‐treated device, proving the ability of healing trap sites of BFN. As was discussed above, the formation of halogen bond could stabilize under‐coordinated iodine ions, which was considered as a type of deep‐level charge trap in perovskites.…”

A bismuth silver pnictohalide alternative to perovskite in fully-printable triple-mesoscopic solar cells

“…Printable triplemesoscopic solar cells (TM-SCs) opened a new chapter of PSCs with promising power conversion efficiency (PCE) up to 16.53%, which meets the scale-up commercialisation requirements, such as low cost and easy fabrication. [1][2][3] TM-SCs consist of mesoporous TiO 2 and ZrO 2 layers covered with a porous carbon lm. Unlike the conventional PSCs, the TM-SCs can be fabricated by screen-printing, and the device can be lled with the perovskite by drop-casting.…”

Efficient and stable full-printed mesoscopic perovskite solar cells with potassium hexafluorophosphate additives

“…25 The longer alkyl chain of OTAC can improve the hydrophobicity of the device and correspondingly improve the device stability, while the existence of long alkyl chains is, to a certain extent, detrimental to the filling of the mesopores. 25 Recently, Liu et al used D-sorbitol hexaacetate (DSHA) containing a carbonyl group as an additive, and the wettability and diffusivity of perovskite precursor solution was enhanced, which greatly raised the filling of perovskite material in the mesoporous pore layer. 18 The carbonyl of the DSHA can react with uncoordinated Pb 2+ and reduce those defects, resulting in a relatively higher PCE of 14.33%.…”