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The increasing global demand for energy and growing environmental concerns emphasize the crucial role of solar energy as a sustainable and nondepletable resource. Solar cells, particularly dye‐sensitized solar cells (DSSCs), have gained prominence due to their efficient conversion of solar power, ecofriendly manufacturing processes, and noteworthy stability. Current research in sustainable energy focuses on transitioning from metal‐based to metal‐free organic materials. Tandem solar cells, combining n‐type and p‐type semiconductors sensitized with diverse photoactive dyes, show potential to surpass thermodynamic limits in photon conversion efficiency. Notably, the exploration of n‐type DSSCs as photoanodes in tandem architectures is promising. However, the absence of efficient p‐type photoactive cathodes remains a significant obstacle. Global research efforts are dedicated to addressing charge recombination issues in NiO‐based devices to enhance the efficiency of p‐type DSSCs. The success of any DSSC hinges on the selection of dyes/sensitizers with suitable anchoring groups, wide absorption in the visible–NIR region, and a high extinction coefficient. This article comprehensively reviews advancements in developing highly efficient p‐type sensitizers, emphasizing their pivotal role in unlocking the full potential of tandem solar cells. [ABSTRACT FROM AUTHOR]

Finding new efficient p‐type sensitizers for NiO photocathodes is a great challenge for the development of promising low‐cost tandem dye‐sensitized solar cells (DSSCs). Now, the focus of researchers investigating these cells has been to create high‐performance p‐type systems. With this intention, herein, the design and synthesis of six new phenoxazine‐based donor–acceptor (D–A)‐configured organic dyes PO1–6 was reported, comprising different acceptor moieties specially designed for the sensitization of mesoporous p‐type semiconductor NiO for the construction of p‐type DSSCs (p‐DSSCs). This work includes structural, photophysical, thermal, electrochemical, theoretical, and photoelectrochemical studies of these dyes, including evaluation of their structure‐property relationships. The optical studies revealed that PO1–6 displayed adequate absorption and emission features in the range of 480–550 and 560–650 nm, respectively, with a bandgap in the order of 2.05–2.40 eV, and their thermodynamic parameters favored an efficient interfacial charge transfer involving NiO. Among the six new dyes, the device based on sensitizer PO2 carrying electron‐withdrawing 1,3‐diethyl‐2‐thiobarbituric acid achieved the highest power conversion efficiency of 0.031 % (short‐circuit current density=0.89 mA cm−2, open‐circuit voltage=101 mV, and fill factor=35 %). Conclusively, the study furnishes an understanding of the intricacies involved in the structural modification of phenoxazine‐based sensitizers to further ameliorate the performance of the p‐type DSSCs. [ABSTRACT FROM AUTHOR]

An organic photosensitizer (DP-1) with D-A-π-A architecture was systematically analyzed along with our previously reported dye N 1. In the design, the dyes carry carbazole as donor, thiophene acetonitrile as π-spacer connected to varied acceptor/anchoring unit i. e., cyanoacrylic acid (N 1) and 4-aminobenzoic acid (DP-1). Generally, cyanoacrylic acid and carboxyl groups have been investigated extensively as effective electron acceptor/anchoring unit for the design of the sensitizer for dye-sensitized solar cells (DSSC) application and displayed superior photon conversion efficiency. In the present work, both the dyes were taken up for various studies focusing on photophysical, electrochemical, theoretical and photovoltaic investigation in the corresponding solar cells. From the photophysical and electrochemical studies it was established that, the both dyes show upright thermodynamic feasibility for electrochemical processes in the cell i. e., both electron and dye regeneration. Also, the DFT studies appends the existence of feasible HOMO-LUMO charge distribution. Finally, the devices fabricated by employing these dyes as sensitizer with 10 mM DCA as co-adsorbent. The device based on N 1 displayed improved photon conversion efficiency compared to the cell sensitized using DP-1. This work may provide a new strategy for designing efficient photosensitizers to further ameliorate the DSSCs performance. An organic photosensitizer (DP-1) with D-A-π-A architecture was systematically analyzed along with our previously reported dye N 1. The photovoltaic studies shown that, the device based on DP-1 displayed PCE of 2. 60% (J SC = 5. 95 mAcm −2 , V OC = 0. 59 V , FF = 73. 3%) in comparison to N 1 sensitized device with PCE of 3. 21% (J SC = 8. 75 mAcm −2 , V OC = 0. 57 V , FF = 64. 7%). Unlabelled Image • Designed and synthesized a new organic dye (DP-1) with D-A-π-A architecture • It was systematically analyzed along with our previously reported dye N 1. • The devices fabricated by using these sensitizers with 10 mM DCA as co-adsorbent. • The device DP-1 displayed PCE of 2. 60% in comparison to device N 1 with PCE of 3. 21 %. [ABSTRACT FROM AUTHOR]